How to use the mypy.subtypes.is_subtype function in mypy

return overload_arg_similarity(actual.ret_type, formal.item)
        else:
            return 0
    if isinstance(formal, Instance):
        if isinstance(actual, CallableType):
            actual = actual.fallback
        if isinstance(actual, Overloaded):
            actual = actual.items()[0].fallback
        if isinstance(actual, TupleType):
            actual = actual.fallback
        if isinstance(actual, Instance):
            # First perform a quick check (as an optimization) and fall back to generic
            # subtyping algorithm if type promotions are possible (e.g., int vs. float).
            if formal.type in actual.type.mro:
                return 2
            elif actual.type._promote and is_subtype(actual, formal):
                return 1
            else:
                return 0
        elif isinstance(actual, TypeType):
            if formal.type.fullname() in {"builtins.object", "builtins.type"}:
                return 2
            else:
                return 0
        else:
            return 0
    if isinstance(actual, UnboundType) or isinstance(formal, UnboundType):
        # Either actual or formal is the result of an error; shut up.
        return 2
    # Fall back to a conservative equality check for the remaining kinds of type.
    return 2 if is_same_type(erasetype.erase_type(actual), erasetype.erase_type(formal)) else 0

def type_is_iterable(self, type: Type) -> bool:
        return (is_subtype(type, self.named_generic_type('typing.Iterable',
                                                        [AnyType()])) and
                isinstance(type, Instance))

if isinstance(s, NoneTyp) and not isinstance(t, NoneTyp):
        s, t = t, s

    if isinstance(s, UninhabitedType) and not isinstance(t, UninhabitedType):
        s, t = t, s

    value = t.accept(TypeJoinVisitor(s))

    if value is None:
        # XXX this code path probably should be avoided.
        # It seems to happen when a line (x = y) is a type error, and
        # it's not clear that assuming that x is arbitrary afterward
        # is a good idea.
        return declaration

    if declaration is None or is_subtype(value, declaration):
        return value

    return declaration

def check_arg(self, caller_type: Type, original_caller_type: Type,
                  caller_kind: int,
                  callee_type: Type, n: int, m: int, callee: CallableType,
                  context: Context, messages: MessageBuilder) -> None:
        """Check the type of a single argument in a call."""
        if isinstance(caller_type, DeletedType):
            messages.deleted_as_rvalue(caller_type, context)
        # Only non-abstract class can be given where Type[...] is expected...
        elif (isinstance(caller_type, CallableType) and isinstance(callee_type, TypeType) and
              caller_type.is_type_obj() and caller_type.type_object().is_abstract and
              isinstance(callee_type.item, Instance) and callee_type.item.type.is_abstract and
              # ...except for classmethod first argument
              not caller_type.is_classmethod_class):
            messages.fail("Only non-abstract class can be given where '{}' is expected"
                          .format(callee_type), context)
        elif not is_subtype(caller_type, callee_type):
            if self.chk.should_suppress_optional_error([caller_type, callee_type]):
                return
            messages.incompatible_argument(n, m, callee, original_caller_type,
                                           caller_kind, context)

def is_valid_keyword_var_arg(self, typ: Type) -> bool:
        """Is a type valid as a **kwargs argument?"""
        if self.chk.options.python_version[0] >= 3:
            return is_subtype(typ, self.chk.named_generic_type(
                'builtins.dict', [self.named_type('builtins.str'),
                                  AnyType()]))
        else:
            return (
                is_subtype(typ, self.chk.named_generic_type(
                    'builtins.dict',
                    [self.named_type('builtins.str'),
                     AnyType()]))
                or
                is_subtype(typ, self.chk.named_generic_type(
                    'builtins.dict',
                    [self.named_type('builtins.unicode'),
                     AnyType()])))

if isinstance(c_typ, Instance) and c_typ.last_known_value:
                c_typ = c_typ.last_known_value
            if isinstance(c_typ, LiteralType) and isinstance(c_typ.value, str):
                if len(c_typ.value) != 1:
                    self.msg.requires_int_or_char(call, format_call=True)
        if (not spec.type or spec.type == 's') and not spec.conversion:
            if self.chk.options.python_version >= (3, 0):
                if has_type_component(actual_type, 'builtins.bytes'):
                    self.msg.fail("On Python 3 '{}'.format(b'abc') produces \"b'abc'\";"
                                  " use !r if this is a desired behavior", call,
                                  code=codes.STR_BYTES_PY3)
        if spec.flags:
            numeric_types = UnionType([self.named_type('builtins.int'),
                                       self.named_type('builtins.float')])
            if (spec.type and spec.type not in NUMERIC_TYPES_NEW or
                    not spec.type and not is_subtype(actual_type, numeric_types) and
                    not custom_special_method(actual_type, '__format__')):
                self.msg.fail('Numeric flags are only allowed for numeric types', call,
                              code=codes.STRING_FORMATTING)

def is_generator_return_type(self, typ: Type, is_coroutine: bool) -> bool:
        """Is `typ` a valid type for a generator/coroutine?

        True if `typ` is a *supertype* of Generator or Awaitable.
        Also true it it's *exactly* AwaitableGenerator (modulo type parameters).
        """
        if is_coroutine:
            # This means we're in Python 3.5 or later.
            at = self.named_generic_type('typing.Awaitable', [AnyType()])
            if is_subtype(at, typ):
                return True
        else:
            gt = self.named_generic_type('typing.Generator', [AnyType(), AnyType(), AnyType()])
            if is_subtype(gt, typ):
                return True
        return isinstance(typ, Instance) and typ.type.fullname() == 'typing.AwaitableGenerator'

def check_override(self, override: FunctionLike, original: FunctionLike,
                       name: str, name_in_super: str, supertype: str,
                       node: Context) -> None:
        """Check a method override with given signatures.

        Arguments:
          override:  The signature of the overriding method.
          original:  The signature of the original supertype method.
          name:      The name of the subtype. This and the next argument are
                     only used for generating error messages.
          supertype: The name of the supertype.
        """
        # Use boolean variable to clarify code.
        fail = False
        if not is_subtype(override, original):
            fail = True
        elif (not isinstance(original, Overloaded) and
              isinstance(override, Overloaded) and
              name in nodes.reverse_op_methods.keys()):
            # Operator method overrides cannot introduce overloading, as
            # this could be unsafe with reverse operator methods.
            fail = True

        if fail:
            emitted_msg = False
            if (isinstance(override, CallableType) and
                    isinstance(original, CallableType) and
                    len(override.arg_types) == len(original.arg_types) and
                    override.min_args == original.min_args):
                # Give more detailed messages for the common case of both
                # signatures having the same number of arguments and no

# Type argument counts were checked in the main semantic analyzer pass. We assume
        # that the counts are correct here.
        info = t.type
        for (i, arg), tvar in zip(enumerate(t.args), info.defn.type_vars):
            if tvar.values:
                if isinstance(arg, TypeVarType):
                    arg_values = arg.values
                    if not arg_values:
                        self.fail('Type variable "{}" not valid as type '
                                  'argument value for "{}"'.format(
                                      arg.name, info.name), t, code=codes.TYPE_VAR)
                        continue
                else:
                    arg_values = [arg]
                self.check_type_var_values(info, arg_values, tvar.name, tvar.values, i + 1, t)
            if not is_subtype(arg, tvar.upper_bound):
                self.fail('Type argument "{}" of "{}" must be '
                          'a subtype of "{}"'.format(
                              arg, info.name, tvar.upper_bound), t, code=codes.TYPE_VAR)
        super().visit_instance(t)

left = left.fallback
            right = right.fallback
        else:
            return False
    elif isinstance(left, LiteralType):
        left = left.fallback
    elif isinstance(right, LiteralType):
        right = right.fallback

    # Finally, we handle the case where left and right are instances.

    if isinstance(left, Instance) and isinstance(right, Instance):
        # First we need to handle promotions and structural compatibility for instances
        # that came as fallbacks, so simply call is_subtype() to avoid code duplication.
        if (is_subtype(left, right, ignore_promotions=ignore_promotions)
                or is_subtype(right, left, ignore_promotions=ignore_promotions)):
            return True

        # Two unrelated types cannot be partially overlapping: they're disjoint.
        if left.type.has_base(right.type.fullname):
            left = map_instance_to_supertype(left, right.type)
        elif right.type.has_base(left.type.fullname):
            right = map_instance_to_supertype(right, left.type)
        else:
            return False

        if len(left.args) == len(right.args):
            # Note: we don't really care about variance here, since the overlapping check
            # is symmetric and since we want to return 'True' even for partial overlaps.
            #
            # For example, suppose we have two types Wrapper[Parent] and Wrapper[Child].
            # It doesn't matter whether Wrapper is covariant or contravariant since