class_docstr: Common part for ConditionalKeyBindings and _MergedKeyBindings.
docstr: If `self._last_version` is outdated, then this should update
  the version and `self._bindings2`.
docstr_tok: ["If","`","self._last_version","`","is","outdated",",","then","this","should","update","the","version","and","`","self._bindings2","`","."]
code: def _update_cache(self) -> None:
      """
      If `self._last_version` is outdated, then this should update
      the version and `self._bindings2`.
      """
      raise NotImplementedError
  
imports: from __future__ import annotations
  from abc import ABCMeta, abstractmethod, abstractproperty
  from inspect import isawaitable
  from typing import TYPE_CHECKING, Any, Callable, Coroutine, Hashable, Sequence, Tuple, TypeVar, Union, cast
  from prompt_toolkit.cache import SimpleCache
  from prompt_toolkit.filters import FilterOrBool, Never, to_filter
  from prompt_toolkit.keys import KEY_ALIASES, Keys
label_desc: Use image node_id 2 for calling the _Proxy obj's underlying member method code with example usage: obj._update_cache() without return types