# Buggy code
def check_method_override(self, defn: Union[FuncBase, Decorator]) -> None:
    """Check if function definition is compatible with base classes."""
    # Check against definitions in base classes.
    for base in defn.info.mro[1:]:
        self.check_method_or_accessor_override_for_base(defn, base)


# Traceback (AssertionError)
pymc3/model.py:672: error: Decorated property not supported
pymc3/variational/opvi.py:1556: error: Decorated property not supported
pymc3/variational/flows.py:193: error: Decorated property not supported
pymc3/__init__.py:25: error: Name 'utils' already defined (by an import)
pymc3/data.py:226: error: Need type annotation for 'RNG'
Traceback (most recent call last):
File "/Users/rpg/Library/Python/3.7/bin/mypy", line 11, in <module>
sys.exit(console_entry())
File "/Users/rpg/Library/Python/3.7/lib/python/site-packages/mypy/__main__.py", line 7, in console_entry
main(None)
File "/Users/rpg/Library/Python/3.7/lib/python/site-packages/mypy/main.py", line 91, in main
res = type_check_only(sources, bin_dir, options, flush_errors, fscache)  # noqa
File "/Users/rpg/Library/Python/3.7/lib/python/site-packages/mypy/main.py", line 148, in type_check_only
fscache=fscache)
File "/Users/rpg/Library/Python/3.7/lib/python/site-packages/mypy/build.py", line 177, in build
flush_errors, fscache)
File "/Users/rpg/Library/Python/3.7/lib/python/site-packages/mypy/build.py", line 350, in _build
graph = dispatch(sources, manager)
File "/Users/rpg/Library/Python/3.7/lib/python/site-packages/mypy/build.py", line 2560, in dispatch
process_graph(graph, manager)
File "/Users/rpg/Library/Python/3.7/lib/python/site-packages/mypy/build.py", line 2853, in process_graph
process_stale_scc(graph, scc, manager)
File "/Users/rpg/Library/Python/3.7/lib/python/site-packages/mypy/build.py", line 2976, in process_stale_scc
graph[id].type_check_first_pass()
File "/Users/rpg/Library/Python/3.7/lib/python/site-packages/mypy/build.py", line 2151, in type_check_first_pass
self.type_checker().check_first_pass()
File "/Users/rpg/Library/Python/3.7/lib/python/site-packages/mypy/checker.py", line 253, in check_first_pass
self.accept(d)
File "/Users/rpg/Library/Python/3.7/lib/python/site-packages/mypy/checker.py", line 352, in accept
stmt.accept(self)
File "/Users/rpg/Library/Python/3.7/lib/python/site-packages/mypy/nodes.py", line 808, in accept
return visitor.visit_class_def(self)
File "/Users/rpg/Library/Python/3.7/lib/python/site-packages/mypy/checker.py", line 1368, in visit_class_def
self.accept(defn.defs)
File "/Users/rpg/Library/Python/3.7/lib/python/site-packages/mypy/checker.py", line 352, in accept
stmt.accept(self)
File "/Users/rpg/Library/Python/3.7/lib/python/site-packages/mypy/nodes.py", line 873, in accept
return visitor.visit_block(self)
File "/Users/rpg/Library/Python/3.7/lib/python/site-packages/mypy/checker.py", line 1514, in visit_block
self.accept(s)
File "/Users/rpg/Library/Python/3.7/lib/python/site-packages/mypy/checker.py", line 352, in accept
stmt.accept(self)
File "/Users/rpg/Library/Python/3.7/lib/python/site-packages/mypy/nodes.py", line 443, in accept
return visitor.visit_overloaded_func_def(self)
File "/Users/rpg/Library/Python/3.7/lib/python/site-packages/mypy/checker.py", line 385, in visit_overloaded_func_def
self._visit_overloaded_func_def(defn)
File "/Users/rpg/Library/Python/3.7/lib/python/site-packages/mypy/checker.py", line 409, in _visit_overloaded_func_def
self.check_method_override(defn)
File "/Users/rpg/Library/Python/3.7/lib/python/site-packages/mypy/checker.py", line 1198, in check_method_override
self.check_method_or_accessor_override_for_base(defn, base)
File "/Users/rpg/Library/Python/3.7/lib/python/site-packages/mypy/checker.py", line 1208, in check_method_or_accessor_override_for_base
self.check_method_override_for_base_with_name(defn, name, base)
File "/Users/rpg/Library/Python/3.7/lib/python/site-packages/mypy/checker.py", line 1252, in check_method_override_for_base_with_name
assert False, str(base_attr.node)
AssertionError: Var(sampler_vars)

# Fixed code
def check_method_override(
    self, defn: Union[FuncDef, OverloadedFuncDef, Decorator]
) -> None:
    """Check if function definition is compatible with base classes.

    This may defer the method if a signature is not available in at least one base class.
    """
    # Check against definitions in base classes.
    for base in defn.info.mro[1:]:
        if self.check_method_or_accessor_override_for_base(defn, base):
            # Node was deferred, we will have another attempt later.
            return