class_docstr: Input for use in a `DummyApplication`
  
  If used in an actual application, it will make the application render
  itself once and exit immediately, due to an `EOFError`.
code: def attach(
      self, input_ready_callback: Callable[[], None]
  ) -> ContextManager[None]:
      # Call the callback immediately once after attaching.
      # This tells the callback to call `read_keys` and check the
      # `input.closed` flag, after which it won't receive any keys, but knows
      # that `EOFError` should be raised. This unblocks `read_from_input` in
      # `application.py`.
      input_ready_callback()
  
      return _dummy_context_manager()
  
imports: from __future__ import annotations
  from abc import ABCMeta, abstractmethod, abstractproperty
  from contextlib import contextmanager
  from typing import Callable, ContextManager, Generator
  from prompt_toolkit.key_binding import KeyPress
label_desc: Use image node_id 7 for calling the DummyInput obj's underlying member method code with example usage: obj.attach(input_ready_callback) and returns: _dummy_context_manager