# Buggy code
def get_array_accesses(blocks, accesses={}):
    """returns a dictionary of arrays accessed and their indices."""
    for block in blocks.values():
        for inst in block.body:
            if isinstance(inst, ir.SetItem):
                accesses[inst.target.name] = inst.index.name
            if isinstance(inst, ir.StaticSetItem):
                accesses[inst.target.name] = inst.index_var.name
            if isinstance(inst, ir.Assign):
                lhs = inst.target.name
                rhs = inst.value
                if isinstance(rhs, ir.Expr) and rhs.op == "getitem":
                    accesses[rhs.value.name] = rhs.index.name
                if isinstance(rhs, ir.Expr) and rhs.op == "static_getitem":
                    accesses[rhs.value.name] = rhs.index_var.name
            for T, f in array_accesses_extensions.items():
                if isinstance(inst, T):
                    f(inst, accesses)
    return accesses


# Traceback (TypeError)
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-15-3b23f7331ceb> in <module>()
----> 1 @jit(arg_types=[numba.double], ret_type=numba.double)
2 def is_REALLY_five(some_value):
3     for i in range(5):
4         if some_value == 5.0:
5             return 1.0

/Library/Frameworks/EPD64.framework/Versions/7.3/lib/python2.7/site-packages/numba/decorators.pyc in _jit(func)
77                   "garbage collected!" % (func,))
78         t = Translate(func, *args, **kws)
---> 79         t.translate()
80         __tr_map__[func] = t
81         return t.get_ctypes_func(llvm)

/Library/Frameworks/EPD64.framework/Versions/7.3/lib/python2.7/site-packages/numba/translate.pyc in translate(self)
926                     # Ensure we are playing with locals that might
927                     # actually precede the next block.
--> 928                     self.check_locals(i)
929
930                 self.crnt_block = i

/Library/Frameworks/EPD64.framework/Versions/7.3/lib/python2.7/site-packages/numba/translate.pyc in check_locals(self, i)
1135                 else:
1136                     assert next_locals is not None, "Internal compiler error!"
-> 1137             self._locals = next_locals[:]
1138
1139     def get_ctypes_func(self, llvm=True):

TypeError: 'NoneType' object has no attribute '__getitem__'

# Fixed code
def get_array_accesses(blocks, accesses=None):
    """returns a dictionary of arrays accessed and their indices."""
    if accesses is None:
        accesses = {}

    for block in blocks.values():
        for inst in block.body:
            if isinstance(inst, ir.SetItem):
                accesses[inst.target.name] = inst.index.name
            if isinstance(inst, ir.StaticSetItem):
                accesses[inst.target.name] = inst.index_var.name
            if isinstance(inst, ir.Assign):
                lhs = inst.target.name
                rhs = inst.value
                if isinstance(rhs, ir.Expr) and rhs.op == "getitem":
                    accesses[rhs.value.name] = rhs.index.name
                if isinstance(rhs, ir.Expr) and rhs.op == "static_getitem":
                    accesses[rhs.value.name] = rhs.index_var.name
            for T, f in array_accesses_extensions.items():
                if isinstance(inst, T):
                    f(inst, accesses)
    return accesses