code: def mypy_instance_typing() -> None:
      class T(HasTraits):
          inst = Instance(Foo)
          oinst = Instance(Foo, allow_none=True)
          oinst_string = Instance("Foo", allow_none=True)
  
      t = T()
      reveal_type(t.inst)  # R: tests.test_typing.Foo
      reveal_type(
          T.inst
      )  # R: traitlets.traitlets.Instance[tests.test_typing.Foo]
      reveal_type(
          T.inst.tag(sync=True)
      )  # R: traitlets.traitlets.Instance[tests.test_typing.Foo]
      reveal_type(t.oinst)  # R: Union[tests.test_typing.Foo, None]
      reveal_type(t.oinst_string)  # R: Union[Any, None]
      reveal_type(
          T.oinst
      )  # R: traitlets.traitlets.Instance[Union[tests.test_typing.Foo, None]]
      reveal_type(
          T.oinst.tag(  # R: traitlets.traitlets.Instance[Union[tests.test_typing.Foo, None]]
              sync=True
          )
      )
      t.inst = "foo"  # E: Incompatible types in assignment (expression has type "str", variable has type "Foo")  [assignment]
      t.oinst = "foo"  # E: Incompatible types in assignment (expression has type "str", variable has type "Optional[Foo]")  [assignment]
      t.inst = None
  
imports: from __future__ import annotations
  import logging
  import typing
  from abc import ABC
  import pytest
  from traitlets import Any, Bool, CInt, Dict, Enum, HasTraits, Instance, Int, List, Set, TCPAddress, Type, Unicode, Union, default, observe, validate
  from traitlets.config import Config
label_desc: Use image node_id 15 for calling a global function with example usage: mypy_instance_typing() without return types