# Buggy code
def sub_one_annotation(self, node, annot, substs, instantiate_unbound=True):
    """Apply type parameter substitutions to an annotation."""
    if isinstance(annot, abstract.TypeParameter):

        def contains(subst, annot):
            return (
                annot.full_name in subst
                and subst[annot.full_name].bindings
                and not any(
                    isinstance(v, abstract.AMBIGUOUS_OR_EMPTY)
                    for v in subst[annot.full_name].data
                )
            )

        if all(contains(subst, annot) for subst in substs):
            vals = sum((subst[annot.full_name].data for subst in substs), [])
        elif instantiate_unbound:
            vals = annot.instantiate(node).data
        else:
            vals = [annot]
        return self.vm.convert.merge_classes(vals)
    elif isinstance(annot, abstract.ParameterizedClass):
        type_parameters = {
            name: self.sub_one_annotation(node, param, substs, instantiate_unbound)
            for name, param in annot.formal_type_parameters.items()
        }
        # annot may be a subtype of ParameterizedClass, such as TupleClass.
        if isinstance(annot, abstract.LiteralClass):
            # We can't create a LiteralClass because we don't have a concrete value.
            typ = abstract.ParameterizedClass
        else:
            typ = type(annot)
        return typ(annot.base_cls, type_parameters, self.vm, annot.template)
    elif isinstance(annot, abstract.Union):
        options = tuple(
            self.sub_one_annotation(node, o, substs, instantiate_unbound)
            for o in annot.options
        )
        return type(annot)(options, self.vm)
    return annot


# Traceback (AttributeError)
from typing import Any
def __getattr__(name: Any) -> Any: ...
# Caught error in pytype: 'LateAnnotation' object has no attribute 'Bindings'
# Traceback (most recent call last):
#   File "/Users/name/.pyenv/versions/3.7.3/envs/venv/lib/python3.7/site-packages/pytype/io.py", line 131, in check_or_generate_pyi
#     input_filename=options.input, options=options, loader=loader)
#   File "/Users/name/.pyenv/versions/3.7.3/envs/venv/lib/python3.7/site-packages/pytype/io.py", line 89, in generate_pyi
#     analyze.infer_types, input_filename, options, loader)
#   File "/Users/name/.pyenv/versions/3.7.3/envs/venv/lib/python3.7/site-packages/pytype/io.py", line 62, in _call
#     deep=deep)
#   File "/Users/name/.pyenv/versions/3.7.3/envs/venv/lib/python3.7/site-packages/pytype/analyze.py", line 668, in infer_types
#     tracer.exitpoint = tracer.analyze(loc, defs, maximum_depth)
#   File "/Users/name/.pyenv/versions/3.7.3/envs/venv/lib/python3.7/site-packages/pytype/analyze.py", line 407, in analyze
#     return self.analyze_toplevel(node, defs)
#   File "/Users/name/.pyenv/versions/3.7.3/envs/venv/lib/python3.7/site-packages/pytype/analyze.py", line 370, in analyze_toplevel
#     new_node = self.analyze_class(node, value)
#   File "/Users/name/.pyenv/versions/3.7.3/envs/venv/lib/python3.7/site-packages/pytype/analyze.py", line 352, in analyze_class
#     node = self.analyze_method_var(node, name, b)
#   File "/Users/name/.pyenv/versions/3.7.3/envs/venv/lib/python3.7/site-packages/pytype/analyze.py", line 202, in analyze_method_var
#     node2 = self.maybe_analyze_method(node1, val)
#   File "/Users/name/.pyenv/versions/3.7.3/envs/venv/lib/python3.7/site-packages/pytype/analyze.py", line 157, in maybe_analyze_method
#     node, _ = self.call_function_with_args(node, val, args)
#   File "/Users/name/.pyenv/versions/3.7.3/envs/venv/lib/python3.7/site-packages/pytype/analyze.py", line 121, in call_function_with_args
#     new_node, ret = self.call_function_in_frame(node, fvar, *args)
#   File "/Users/name/.pyenv/versions/3.7.3/envs/venv/lib/python3.7/site-packages/pytype/analyze.py", line 132, in call_function_in_frame
#     state, var, args, kwargs, starargs, starstarargs)
#   File "/Users/name/.pyenv/versions/3.7.3/envs/venv/lib/python3.7/site-packages/pytype/vm.py", line 917, in call_function_with_state
#     starstarargs=starstarargs), fallback_to_unsolvable, allow_noreturn=True)
#   File "/Users/name/.pyenv/versions/3.7.3/envs/venv/lib/python3.7/site-packages/pytype/vm.py", line 953, in call_function
#     new_node, one_result = func.call(node, funcv, args)
#   File "/Users/name/.pyenv/versions/3.7.3/envs/venv/lib/python3.7/site-packages/pytype/abstract.py", line 3247, in call
#     alias_map=self.alias_map)
#   File "/Users/name/.pyenv/versions/3.7.3/envs/venv/lib/python3.7/site-packages/pytype/abstract.py", line 3051, in call
#     node2, ret = self.vm.run_frame(frame, node)
#   File "/Users/name/.pyenv/versions/3.7.3/envs/venv/lib/python3.7/site-packages/pytype/vm.py", line 292, in run_frame
#     state = self.run_instruction(op, state)
#   File "/Users/name/.pyenv/versions/3.7.3/envs/venv/lib/python3.7/site-packages/pytype/vm.py", line 253, in run_instruction
#     state = bytecode_fn(state, op)
#   File "/Users/name/.pyenv/versions/3.7.3/envs/venv/lib/python3.7/site-packages/pytype/vm.py", line 1980, in byte_LOAD_ATTR
#     state, val = self.load_attr(state, obj, name)
#   File "/Users/name/.pyenv/versions/3.7.3/envs/venv/lib/python3.7/site-packages/pytype/vm.py", line 1224, in load_attr
#     node, result, errors = self._retrieve_attr(state.node, obj, attr)
#   File "/Users/name/.pyenv/versions/3.7.3/envs/venv/lib/python3.7/site-packages/pytype/vm.py", line 1195, in _retrieve_attr
#     node, val.data, attr, val)
#   File "/Users/name/.pyenv/versions/3.7.3/envs/venv/lib/python3.7/site-packages/pytype/attribute.py", line 65, in get_attribute
#     return self._get_instance_attribute(node, obj, name, valself)
#   File "/Users/name/.pyenv/versions/3.7.3/envs/venv/lib/python3.7/site-packages/pytype/attribute.py", line 234, in _get_instance_attribute
#     return self._get_attribute(node, obj, obj.cls, name, valself)
#   File "/Users/name/.pyenv/versions/3.7.3/envs/venv/lib/python3.7/site-packages/pytype/attribute.py", line 270, in _get_attribute
#     node, attr = self.get_attribute(node, cls, name, valself)
#   File "/Users/name/.pyenv/versions/3.7.3/envs/venv/lib/python3.7/site-packages/pytype/attribute.py", line 58, in get_attribute
#     return self._get_class_attribute(node, obj, name, valself)
#   File "/Users/name/.pyenv/versions/3.7.3/envs/venv/lib/python3.7/site-packages/pytype/attribute.py", line 229, in _get_class_attribute
#     return self._get_attribute(node, cls, meta, name, valself)
#   File "/Users/name/.pyenv/versions/3.7.3/envs/venv/lib/python3.7/site-packages/pytype/attribute.py", line 284, in _get_attribute
#     attr = self._filter_var(node, attr)
#   File "/Users/name/.pyenv/versions/3.7.3/envs/venv/lib/python3.7/site-packages/pytype/attribute.py", line 426, in _filter_var
#     bindings = var.Bindings(node, strict=False)
# AttributeError: 'LateAnnotation' object has no attribute 'Bindings'

# Fixed code
def sub_one_annotation(self, node, annot, substs, instantiate_unbound=True):
    """Apply type parameter substitutions to an annotation."""
    if isinstance(annot, abstract.TypeParameter):

        def contains(subst, annot):
            return (
                annot.full_name in subst
                and subst[annot.full_name].bindings
                and not any(
                    isinstance(v, abstract.AMBIGUOUS_OR_EMPTY)
                    for v in subst[annot.full_name].data
                )
            )

        if all(contains(subst, annot) for subst in substs):
            vals = sum((subst[annot.full_name].data for subst in substs), [])
        elif instantiate_unbound:
            vals = annot.instantiate(node).data
        else:
            vals = [annot]
        return self.vm.convert.merge_classes(vals)
    elif isinstance(annot, abstract.ParameterizedClass):
        type_parameters = {
            name: self.sub_one_annotation(node, param, substs, instantiate_unbound)
            for name, param in annot.formal_type_parameters.items()
        }
        # annot may be a subtype of ParameterizedClass, such as TupleClass.
        if isinstance(annot, abstract.LiteralClass):
            # We can't create a LiteralClass because we don't have a concrete value.
            typ = abstract.ParameterizedClass
        else:
            typ = annot.__class__
        return typ(annot.base_cls, type_parameters, self.vm, annot.template)
    elif isinstance(annot, abstract.Union):
        options = tuple(
            self.sub_one_annotation(node, o, substs, instantiate_unbound)
            for o in annot.options
        )
        return annot.__class__(options, self.vm)
    return annot