dis — Disassembler for Python bytecode Source code: Lib/dis.py The dis module supports the analysis of CPython bytecode by disassembling it. The CPython bytecode which this module takes as an input is defined in the file Include/opcode.h and used by the compiler and the interpreter.  CPython implementation detail: Bytecode is an implementation detail of the CPython interpreter. No guarantees are made that bytecode will not be added, removed, or changed between versions of Python. Use of this module should not be considered to work across Python VMs or Python releases.  Changed in version 3.6: Use 2 bytes for each instruction. Previously the number of bytes varied by instruction.   Example: Given the function myfunc(): def myfunc(alist):
    return len(alist)
 the following command can be used to display the disassembly of myfunc(): >>> dis.dis(myfunc)
  2           0 LOAD_GLOBAL              0 (len)
              2 LOAD_FAST                0 (alist)
              4 CALL_FUNCTION            1
              6 RETURN_VALUE
 (The “2” is a line number). Bytecode analysis  New in version 3.4.  The bytecode analysis API allows pieces of Python code to be wrapped in a Bytecode object that provides easy access to details of the compiled code.  
class dis.Bytecode(x, *, first_line=None, current_offset=None)  
Analyse the bytecode corresponding to a function, generator, asynchronous generator, coroutine, method, string of source code, or a code object (as returned by compile()). This is a convenience wrapper around many of the functions listed below, most notably get_instructions(), as iterating over a Bytecode instance yields the bytecode operations as Instruction instances. If first_line is not None, it indicates the line number that should be reported for the first source line in the disassembled code. Otherwise, the source line information (if any) is taken directly from the disassembled code object. If current_offset is not None, it refers to an instruction offset in the disassembled code. Setting this means dis() will display a “current instruction” marker against the specified opcode.  
classmethod from_traceback(tb)  
Construct a Bytecode instance from the given traceback, setting current_offset to the instruction responsible for the exception. 
  
codeobj  
The compiled code object. 
  
first_line  
The first source line of the code object (if available) 
  
dis()  
Return a formatted view of the bytecode operations (the same as printed by dis.dis(), but returned as a multi-line string). 
  
info()  
Return a formatted multi-line string with detailed information about the code object, like code_info(). 
  Changed in version 3.7: This can now handle coroutine and asynchronous generator objects.  
 Example: >>> bytecode = dis.Bytecode(myfunc)
>>> for instr in bytecode:
...     print(instr.opname)
...
LOAD_GLOBAL
LOAD_FAST
CALL_FUNCTION
RETURN_VALUE
 Analysis functions The dis module also defines the following analysis functions that convert the input directly to the desired output. They can be useful if only a single operation is being performed, so the intermediate analysis object isn’t useful:  
dis.code_info(x)  
Return a formatted multi-line string with detailed code object information for the supplied function, generator, asynchronous generator, coroutine, method, source code string or code object. Note that the exact contents of code info strings are highly implementation dependent and they may change arbitrarily across Python VMs or Python releases.  New in version 3.2.   Changed in version 3.7: This can now handle coroutine and asynchronous generator objects.  
  
dis.show_code(x, *, file=None)  
Print detailed code object information for the supplied function, method, source code string or code object to file (or sys.stdout if file is not specified). This is a convenient shorthand for print(code_info(x), file=file), intended for interactive exploration at the interpreter prompt.  New in version 3.2.   Changed in version 3.4: Added file parameter.  
  
dis.dis(x=None, *, file=None, depth=None)  
Disassemble the x object. x can denote either a module, a class, a method, a function, a generator, an asynchronous generator, a coroutine, a code object, a string of source code or a byte sequence of raw bytecode. For a module, it disassembles all functions. For a class, it disassembles all methods (including class and static methods). For a code object or sequence of raw bytecode, it prints one line per bytecode instruction. It also recursively disassembles nested code objects (the code of comprehensions, generator expressions and nested functions, and the code used for building nested classes). Strings are first compiled to code objects with the compile() built-in function before being disassembled. If no object is provided, this function disassembles the last traceback. The disassembly is written as text to the supplied file argument if provided and to sys.stdout otherwise. The maximal depth of recursion is limited by depth unless it is None. depth=0 means no recursion.  Changed in version 3.4: Added file parameter.   Changed in version 3.7: Implemented recursive disassembling and added depth parameter.   Changed in version 3.7: This can now handle coroutine and asynchronous generator objects.  
  
dis.distb(tb=None, *, file=None)  
Disassemble the top-of-stack function of a traceback, using the last traceback if none was passed. The instruction causing the exception is indicated. The disassembly is written as text to the supplied file argument if provided and to sys.stdout otherwise.  Changed in version 3.4: Added file parameter.  
  
dis.disassemble(code, lasti=-1, *, file=None)  
dis.disco(code, lasti=-1, *, file=None)  
Disassemble a code object, indicating the last instruction if lasti was provided. The output is divided in the following columns:  the line number, for the first instruction of each line the current instruction, indicated as -->, a labelled instruction, indicated with >>, the address of the instruction, the operation code name, operation parameters, and interpretation of the parameters in parentheses.  The parameter interpretation recognizes local and global variable names, constant values, branch targets, and compare operators. The disassembly is written as text to the supplied file argument if provided and to sys.stdout otherwise.  Changed in version 3.4: Added file parameter.  
  
dis.get_instructions(x, *, first_line=None)  
Return an iterator over the instructions in the supplied function, method, source code string or code object. The iterator generates a series of Instruction named tuples giving the details of each operation in the supplied code. If first_line is not None, it indicates the line number that should be reported for the first source line in the disassembled code. Otherwise, the source line information (if any) is taken directly from the disassembled code object.  New in version 3.4.  
  
dis.findlinestarts(code)  
This generator function uses the co_firstlineno and co_lnotab attributes of the code object code to find the offsets which are starts of lines in the source code. They are generated as (offset, lineno) pairs. See Objects/lnotab_notes.txt for the co_lnotab format and how to decode it.  Changed in version 3.6: Line numbers can be decreasing. Before, they were always increasing.  
  
dis.findlabels(code)  
Detect all offsets in the raw compiled bytecode string code which are jump targets, and return a list of these offsets. 
  
dis.stack_effect(opcode, oparg=None, *, jump=None)  
Compute the stack effect of opcode with argument oparg. If the code has a jump target and jump is True, stack_effect() will return the stack effect of jumping. If jump is False, it will return the stack effect of not jumping. And if jump is None (default), it will return the maximal stack effect of both cases.  New in version 3.4.   Changed in version 3.8: Added jump parameter.  
 Python Bytecode Instructions The get_instructions() function and Bytecode class provide details of bytecode instructions as Instruction instances:  
class dis.Instruction  
Details for a bytecode operation  
opcode  
numeric code for operation, corresponding to the opcode values listed below and the bytecode values in the Opcode collections. 
  
opname  
human readable name for operation 
  
arg  
numeric argument to operation (if any), otherwise None 
  
argval  
resolved arg value (if known), otherwise same as arg 
  
argrepr  
human readable description of operation argument 
  
offset  
start index of operation within bytecode sequence 
  
starts_line  
line started by this opcode (if any), otherwise None 
  
is_jump_target  
True if other code jumps to here, otherwise False 
  New in version 3.4.  
 The Python compiler currently generates the following bytecode instructions. General instructions  
NOP  
Do nothing code. Used as a placeholder by the bytecode optimizer. 
  
POP_TOP  
Removes the top-of-stack (TOS) item. 
  
ROT_TWO  
Swaps the two top-most stack items. 
  
ROT_THREE  
Lifts second and third stack item one position up, moves top down to position three. 
  
ROT_FOUR  
Lifts second, third and fourth stack items one position up, moves top down to position four.  New in version 3.8.  
  
DUP_TOP  
Duplicates the reference on top of the stack.  New in version 3.2.  
  
DUP_TOP_TWO  
Duplicates the two references on top of the stack, leaving them in the same order.  New in version 3.2.  
 Unary operations Unary operations take the top of the stack, apply the operation, and push the result back on the stack.  
UNARY_POSITIVE  
Implements TOS = +TOS. 
  
UNARY_NEGATIVE  
Implements TOS = -TOS. 
  
UNARY_NOT  
Implements TOS = not TOS. 
  
UNARY_INVERT  
Implements TOS = ~TOS. 
  
GET_ITER  
Implements TOS = iter(TOS). 
  
GET_YIELD_FROM_ITER  
If TOS is a generator iterator or coroutine object it is left as is. Otherwise, implements TOS = iter(TOS).  New in version 3.5.  
 Binary operations Binary operations remove the top of the stack (TOS) and the second top-most stack item (TOS1) from the stack. They perform the operation, and put the result back on the stack.  
BINARY_POWER  
Implements TOS = TOS1 ** TOS. 
  
BINARY_MULTIPLY  
Implements TOS = TOS1 * TOS. 
  
BINARY_MATRIX_MULTIPLY  
Implements TOS = TOS1 @ TOS.  New in version 3.5.  
  
BINARY_FLOOR_DIVIDE  
Implements TOS = TOS1 // TOS. 
  
BINARY_TRUE_DIVIDE  
Implements TOS = TOS1 / TOS. 
  
BINARY_MODULO  
Implements TOS = TOS1 % TOS. 
  
BINARY_ADD  
Implements TOS = TOS1 + TOS. 
  
BINARY_SUBTRACT  
Implements TOS = TOS1 - TOS. 
  
BINARY_SUBSCR  
Implements TOS = TOS1[TOS]. 
  
BINARY_LSHIFT  
Implements TOS = TOS1 << TOS. 
  
BINARY_RSHIFT  
Implements TOS = TOS1 >> TOS. 
  
BINARY_AND  
Implements TOS = TOS1 & TOS. 
  
BINARY_XOR  
Implements TOS = TOS1 ^ TOS. 
  
BINARY_OR  
Implements TOS = TOS1 | TOS. 
 In-place operations In-place operations are like binary operations, in that they remove TOS and TOS1, and push the result back on the stack, but the operation is done in-place when TOS1 supports it, and the resulting TOS may be (but does not have to be) the original TOS1.  
INPLACE_POWER  
Implements in-place TOS = TOS1 ** TOS. 
  
INPLACE_MULTIPLY  
Implements in-place TOS = TOS1 * TOS. 
  
INPLACE_MATRIX_MULTIPLY  
Implements in-place TOS = TOS1 @ TOS.  New in version 3.5.  
  
INPLACE_FLOOR_DIVIDE  
Implements in-place TOS = TOS1 // TOS. 
  
INPLACE_TRUE_DIVIDE  
Implements in-place TOS = TOS1 / TOS. 
  
INPLACE_MODULO  
Implements in-place TOS = TOS1 % TOS. 
  
INPLACE_ADD  
Implements in-place TOS = TOS1 + TOS. 
  
INPLACE_SUBTRACT  
Implements in-place TOS = TOS1 - TOS. 
  
INPLACE_LSHIFT  
Implements in-place TOS = TOS1 << TOS. 
  
INPLACE_RSHIFT  
Implements in-place TOS = TOS1 >> TOS. 
  
INPLACE_AND  
Implements in-place TOS = TOS1 & TOS. 
  
INPLACE_XOR  
Implements in-place TOS = TOS1 ^ TOS. 
  
INPLACE_OR  
Implements in-place TOS = TOS1 | TOS. 
  
STORE_SUBSCR  
Implements TOS1[TOS] = TOS2. 
  
DELETE_SUBSCR  
Implements del TOS1[TOS]. 
 Coroutine opcodes  
GET_AWAITABLE  
Implements TOS = get_awaitable(TOS), where get_awaitable(o) returns o if o is a coroutine object or a generator object with the CO_ITERABLE_COROUTINE flag, or resolves o.__await__.  New in version 3.5.  
  
GET_AITER  
Implements TOS = TOS.__aiter__().  New in version 3.5.   Changed in version 3.7: Returning awaitable objects from __aiter__ is no longer supported.  
  
GET_ANEXT  
Implements PUSH(get_awaitable(TOS.__anext__())). See GET_AWAITABLE for details about get_awaitable  New in version 3.5.  
  
END_ASYNC_FOR  
Terminates an async for loop. Handles an exception raised when awaiting a next item. If TOS is StopAsyncIteration pop 7 values from the stack and restore the exception state using the second three of them. Otherwise re-raise the exception using the three values from the stack. An exception handler block is removed from the block stack.  New in version 3.8.  
  
BEFORE_ASYNC_WITH  
Resolves __aenter__ and __aexit__ from the object on top of the stack. Pushes __aexit__ and result of __aenter__() to the stack.  New in version 3.5.  
  
SETUP_ASYNC_WITH  
Creates a new frame object.  New in version 3.5.  
 Miscellaneous opcodes  
PRINT_EXPR  
Implements the expression statement for the interactive mode. TOS is removed from the stack and printed. In non-interactive mode, an expression statement is terminated with POP_TOP. 
  
SET_ADD(i)  
Calls set.add(TOS1[-i], TOS). Used to implement set comprehensions. 
  
LIST_APPEND(i)  
Calls list.append(TOS1[-i], TOS). Used to implement list comprehensions. 
  
MAP_ADD(i)  
Calls dict.__setitem__(TOS1[-i], TOS1, TOS). Used to implement dict comprehensions.  New in version 3.1.   Changed in version 3.8: Map value is TOS and map key is TOS1. Before, those were reversed.  
 For all of the SET_ADD, LIST_APPEND and MAP_ADD instructions, while the added value or key/value pair is popped off, the container object remains on the stack so that it is available for further iterations of the loop.  
RETURN_VALUE  
Returns with TOS to the caller of the function. 
  
YIELD_VALUE  
Pops TOS and yields it from a generator. 
  
YIELD_FROM  
Pops TOS and delegates to it as a subiterator from a generator.  New in version 3.3.  
  
SETUP_ANNOTATIONS  
Checks whether __annotations__ is defined in locals(), if not it is set up to an empty dict. This opcode is only emitted if a class or module body contains variable annotations statically.  New in version 3.6.  
  
IMPORT_STAR  
Loads all symbols not starting with '_' directly from the module TOS to the local namespace. The module is popped after loading all names. This opcode implements from module import *. 
  
POP_BLOCK  
Removes one block from the block stack. Per frame, there is a stack of blocks, denoting try statements, and such. 
  
POP_EXCEPT  
Removes one block from the block stack. The popped block must be an exception handler block, as implicitly created when entering an except handler. In addition to popping extraneous values from the frame stack, the last three popped values are used to restore the exception state. 
  
RERAISE  
Re-raises the exception currently on top of the stack.  New in version 3.9.  
  
WITH_EXCEPT_START  
Calls the function in position 7 on the stack with the top three items on the stack as arguments. Used to implement the call context_manager.__exit__(*exc_info()) when an exception has occurred in a with statement.  New in version 3.9.  
  
LOAD_ASSERTION_ERROR  
Pushes AssertionError onto the stack. Used by the assert statement.  New in version 3.9.  
  
LOAD_BUILD_CLASS  
Pushes builtins.__build_class__() onto the stack. It is later called by CALL_FUNCTION to construct a class. 
  
SETUP_WITH(delta)  
This opcode performs several operations before a with block starts. First, it loads __exit__() from the context manager and pushes it onto the stack for later use by WITH_CLEANUP_START. Then, __enter__() is called, and a finally block pointing to delta is pushed. Finally, the result of calling the __enter__() method is pushed onto the stack. The next opcode will either ignore it (POP_TOP), or store it in (a) variable(s) (STORE_FAST, STORE_NAME, or UNPACK_SEQUENCE).  New in version 3.2.  
 All of the following opcodes use their arguments.  
STORE_NAME(namei)  
Implements name = TOS. namei is the index of name in the attribute co_names of the code object. The compiler tries to use STORE_FAST or STORE_GLOBAL if possible. 
  
DELETE_NAME(namei)  
Implements del name, where namei is the index into co_names attribute of the code object. 
  
UNPACK_SEQUENCE(count)  
Unpacks TOS into count individual values, which are put onto the stack right-to-left. 
  
UNPACK_EX(counts)  
Implements assignment with a starred target: Unpacks an iterable in TOS into individual values, where the total number of values can be smaller than the number of items in the iterable: one of the new values will be a list of all leftover items. The low byte of counts is the number of values before the list value, the high byte of counts the number of values after it. The resulting values are put onto the stack right-to-left. 
  
STORE_ATTR(namei)  
Implements TOS.name = TOS1, where namei is the index of name in co_names. 
  
DELETE_ATTR(namei)  
Implements del TOS.name, using namei as index into co_names. 
  
STORE_GLOBAL(namei)  
Works as STORE_NAME, but stores the name as a global. 
  
DELETE_GLOBAL(namei)  
Works as DELETE_NAME, but deletes a global name. 
  
LOAD_CONST(consti)  
Pushes co_consts[consti] onto the stack. 
  
LOAD_NAME(namei)  
Pushes the value associated with co_names[namei] onto the stack. 
  
BUILD_TUPLE(count)  
Creates a tuple consuming count items from the stack, and pushes the resulting tuple onto the stack. 
  
BUILD_LIST(count)  
Works as BUILD_TUPLE, but creates a list. 
  
BUILD_SET(count)  
Works as BUILD_TUPLE, but creates a set. 
  
BUILD_MAP(count)  
Pushes a new dictionary object onto the stack. Pops 2 * count items so that the dictionary holds count entries: {..., TOS3: TOS2, TOS1: TOS}.  Changed in version 3.5: The dictionary is created from stack items instead of creating an empty dictionary pre-sized to hold count items.  
  
BUILD_CONST_KEY_MAP(count)  
The version of BUILD_MAP specialized for constant keys. Pops the top element on the stack which contains a tuple of keys, then starting from TOS1, pops count values to form values in the built dictionary.  New in version 3.6.  
  
BUILD_STRING(count)  
Concatenates count strings from the stack and pushes the resulting string onto the stack.  New in version 3.6.  
  
LIST_TO_TUPLE  
Pops a list from the stack and pushes a tuple containing the same values.  New in version 3.9.  
  
LIST_EXTEND(i)  
Calls list.extend(TOS1[-i], TOS). Used to build lists.  New in version 3.9.  
  
SET_UPDATE(i)  
Calls set.update(TOS1[-i], TOS). Used to build sets.  New in version 3.9.  
  
DICT_UPDATE(i)  
Calls dict.update(TOS1[-i], TOS). Used to build dicts.  New in version 3.9.  
  
DICT_MERGE  
Like DICT_UPDATE but raises an exception for duplicate keys.  New in version 3.9.  
  
LOAD_ATTR(namei)  
Replaces TOS with getattr(TOS, co_names[namei]). 
  
COMPARE_OP(opname)  
Performs a Boolean operation. The operation name can be found in cmp_op[opname]. 
  
IS_OP(invert)  
Performs is comparison, or is not if invert is 1.  New in version 3.9.  
  
CONTAINS_OP(invert)  
Performs in comparison, or not in if invert is 1.  New in version 3.9.  
  
IMPORT_NAME(namei)  
Imports the module co_names[namei]. TOS and TOS1 are popped and provide the fromlist and level arguments of __import__(). The module object is pushed onto the stack. The current namespace is not affected: for a proper import statement, a subsequent STORE_FAST instruction modifies the namespace. 
  
IMPORT_FROM(namei)  
Loads the attribute co_names[namei] from the module found in TOS. The resulting object is pushed onto the stack, to be subsequently stored by a STORE_FAST instruction. 
  
JUMP_FORWARD(delta)  
Increments bytecode counter by delta. 
  
POP_JUMP_IF_TRUE(target)  
If TOS is true, sets the bytecode counter to target. TOS is popped.  New in version 3.1.  
  
POP_JUMP_IF_FALSE(target)  
If TOS is false, sets the bytecode counter to target. TOS is popped.  New in version 3.1.  
  
JUMP_IF_NOT_EXC_MATCH(target)  
Tests whether the second value on the stack is an exception matching TOS, and jumps if it is not. Pops two values from the stack.  New in version 3.9.  
  
JUMP_IF_TRUE_OR_POP(target)  
If TOS is true, sets the bytecode counter to target and leaves TOS on the stack. Otherwise (TOS is false), TOS is popped.  New in version 3.1.  
  
JUMP_IF_FALSE_OR_POP(target)  
If TOS is false, sets the bytecode counter to target and leaves TOS on the stack. Otherwise (TOS is true), TOS is popped.  New in version 3.1.  
  
JUMP_ABSOLUTE(target)  
Set bytecode counter to target. 
  
FOR_ITER(delta)  
TOS is an iterator. Call its __next__() method. If this yields a new value, push it on the stack (leaving the iterator below it). If the iterator indicates it is exhausted, TOS is popped, and the byte code counter is incremented by delta. 
  
LOAD_GLOBAL(namei)  
Loads the global named co_names[namei] onto the stack. 
  
SETUP_FINALLY(delta)  
Pushes a try block from a try-finally or try-except clause onto the block stack. delta points to the finally block or the first except block. 
  
LOAD_FAST(var_num)  
Pushes a reference to the local co_varnames[var_num] onto the stack. 
  
STORE_FAST(var_num)  
Stores TOS into the local co_varnames[var_num]. 
  
DELETE_FAST(var_num)  
Deletes local co_varnames[var_num]. 
  
LOAD_CLOSURE(i)  
Pushes a reference to the cell contained in slot i of the cell and free variable storage. The name of the variable is co_cellvars[i] if i is less than the length of co_cellvars. Otherwise it is co_freevars[i -
len(co_cellvars)]. 
  
LOAD_DEREF(i)  
Loads the cell contained in slot i of the cell and free variable storage. Pushes a reference to the object the cell contains on the stack. 
  
LOAD_CLASSDEREF(i)  
Much like LOAD_DEREF but first checks the locals dictionary before consulting the cell. This is used for loading free variables in class bodies.  New in version 3.4.  
  
STORE_DEREF(i)  
Stores TOS into the cell contained in slot i of the cell and free variable storage. 
  
DELETE_DEREF(i)  
Empties the cell contained in slot i of the cell and free variable storage. Used by the del statement.  New in version 3.2.  
  
RAISE_VARARGS(argc)  
Raises an exception using one of the 3 forms of the raise statement, depending on the value of argc:  0: raise (re-raise previous exception) 1: raise TOS (raise exception instance or type at TOS) 2: raise TOS1 from TOS (raise exception instance or type at TOS1 with __cause__ set to TOS)  
  
CALL_FUNCTION(argc)  
Calls a callable object with positional arguments. argc indicates the number of positional arguments. The top of the stack contains positional arguments, with the right-most argument on top. Below the arguments is a callable object to call. CALL_FUNCTION pops all arguments and the callable object off the stack, calls the callable object with those arguments, and pushes the return value returned by the callable object.  Changed in version 3.6: This opcode is used only for calls with positional arguments.  
  
CALL_FUNCTION_KW(argc)  
Calls a callable object with positional (if any) and keyword arguments. argc indicates the total number of positional and keyword arguments. The top element on the stack contains a tuple with the names of the keyword arguments, which must be strings. Below that are the values for the keyword arguments, in the order corresponding to the tuple. Below that are positional arguments, with the right-most parameter on top. Below the arguments is a callable object to call. CALL_FUNCTION_KW pops all arguments and the callable object off the stack, calls the callable object with those arguments, and pushes the return value returned by the callable object.  Changed in version 3.6: Keyword arguments are packed in a tuple instead of a dictionary, argc indicates the total number of arguments.  
  
CALL_FUNCTION_EX(flags)  
Calls a callable object with variable set of positional and keyword arguments. If the lowest bit of flags is set, the top of the stack contains a mapping object containing additional keyword arguments. Before the callable is called, the mapping object and iterable object are each “unpacked” and their contents passed in as keyword and positional arguments respectively. CALL_FUNCTION_EX pops all arguments and the callable object off the stack, calls the callable object with those arguments, and pushes the return value returned by the callable object.  New in version 3.6.  
  
LOAD_METHOD(namei)  
Loads a method named co_names[namei] from the TOS object. TOS is popped. This bytecode distinguishes two cases: if TOS has a method with the correct name, the bytecode pushes the unbound method and TOS. TOS will be used as the first argument (self) by CALL_METHOD when calling the unbound method. Otherwise, NULL and the object return by the attribute lookup are pushed.  New in version 3.7.  
  
CALL_METHOD(argc)  
Calls a method. argc is the number of positional arguments. Keyword arguments are not supported. This opcode is designed to be used with LOAD_METHOD. Positional arguments are on top of the stack. Below them, the two items described in LOAD_METHOD are on the stack (either self and an unbound method object or NULL and an arbitrary callable). All of them are popped and the return value is pushed.  New in version 3.7.  
  
MAKE_FUNCTION(flags)  
Pushes a new function object on the stack. From bottom to top, the consumed stack must consist of values if the argument carries a specified flag value  
0x01 a tuple of default values for positional-only and positional-or-keyword parameters in positional order 
0x02 a dictionary of keyword-only parameters’ default values 
0x04 an annotation dictionary 
0x08 a tuple containing cells for free variables, making a closure the code associated with the function (at TOS1) the qualified name of the function (at TOS)  
  
BUILD_SLICE(argc)  
Pushes a slice object on the stack. argc must be 2 or 3. If it is 2, slice(TOS1, TOS) is pushed; if it is 3, slice(TOS2, TOS1, TOS) is pushed. See the slice() built-in function for more information. 
  
EXTENDED_ARG(ext)  
Prefixes any opcode which has an argument too big to fit into the default one byte. ext holds an additional byte which act as higher bits in the argument. For each opcode, at most three prefixal EXTENDED_ARG are allowed, forming an argument from two-byte to four-byte. 
  
FORMAT_VALUE(flags)  
Used for implementing formatted literal strings (f-strings). Pops an optional fmt_spec from the stack, then a required value. flags is interpreted as follows:  
(flags & 0x03) == 0x00: value is formatted as-is. 
(flags & 0x03) == 0x01: call str() on value before formatting it. 
(flags & 0x03) == 0x02: call repr() on value before formatting it. 
(flags & 0x03) == 0x03: call ascii() on value before formatting it. 
(flags & 0x04) == 0x04: pop fmt_spec from the stack and use it, else use an empty fmt_spec.  Formatting is performed using PyObject_Format(). The result is pushed on the stack.  New in version 3.6.  
  
HAVE_ARGUMENT  
This is not really an opcode. It identifies the dividing line between opcodes which don’t use their argument and those that do (< HAVE_ARGUMENT and >= HAVE_ARGUMENT, respectively).  Changed in version 3.6: Now every instruction has an argument, but opcodes < HAVE_ARGUMENT ignore it. Before, only opcodes >= HAVE_ARGUMENT had an argument.  
 Opcode collections These collections are provided for automatic introspection of bytecode instructions:  
dis.opname  
Sequence of operation names, indexable using the bytecode. 
  
dis.opmap  
Dictionary mapping operation names to bytecodes. 
  
dis.cmp_op  
Sequence of all compare operation names. 
  
dis.hasconst  
Sequence of bytecodes that access a constant. 
  
dis.hasfree  
Sequence of bytecodes that access a free variable (note that ‘free’ in this context refers to names in the current scope that are referenced by inner scopes or names in outer scopes that are referenced from this scope. It does not include references to global or builtin scopes). 
  
dis.hasname  
Sequence of bytecodes that access an attribute by name. 
  
dis.hasjrel  
Sequence of bytecodes that have a relative jump target. 
  
dis.hasjabs  
Sequence of bytecodes that have an absolute jump target. 
  
dis.haslocal  
Sequence of bytecodes that access a local variable. 
  
dis.hascompare  
Sequence of bytecodes of Boolean operations.