class_docstr: Cache for remember which style strings don't render the default output
  style (default fg/bg, no underline and no reverse and no blink). That way
  we know that we should render these cells, even when they're empty (when
  they contain a space).
  
  Note: we don't consider bold/italic/hidden because they don't change the
  output if there's no text in the cell.
class_docstr_tok: ["Cache","for","remember","which","style","strings","do","n't","render","the","default","output","style","(","default","fg\/bg",",","no","underline","and","no","reverse","and","no","blink",")",".","That","way","we","know","that","we","should","render","these","cells",",","even","when","they","'re","empty","(","when","they","contain","a","space",")",".","Note",":","we","do","n't","consider","bold\/italic\/hidden","because","they","do","n't","change","the","output","if","there","'s","no","text","in","the","cell","."]
code: def __missing__(self, style_str: str) -> bool:
      attrs = self.style_string_to_attrs[style_str]
      is_default = bool(
          attrs.color
          or attrs.bgcolor
          or attrs.underline
          or attrs.strike
          or attrs.blink
          or attrs.reverse
      )
  
      self[style_str] = is_default
      return is_default
  
imports: from __future__ import annotations
  from asyncio import FIRST_COMPLETED, Future, ensure_future, sleep, wait
  from collections import deque
  from enum import Enum
  from typing import TYPE_CHECKING, Any, Callable, Dict, Hashable
  from prompt_toolkit.application.current import get_app
  from prompt_toolkit.cursor_shapes import CursorShape
  from prompt_toolkit.data_structures import Point, Size
  from prompt_toolkit.filters import FilterOrBool, to_filter
  from prompt_toolkit.formatted_text import AnyFormattedText, to_formatted_text
  from prompt_toolkit.layout.mouse_handlers import MouseHandlers
  from prompt_toolkit.layout.screen import Char, Screen, WritePosition
  from prompt_toolkit.output import ColorDepth, Output
  from prompt_toolkit.styles import Attrs, BaseStyle, DummyStyleTransformation, StyleTransformation
label_desc: Use image node_id 2 for calling the _StyleStringHasStyleCache obj's underlying member method code with example usage: obj.__missing__(style_str) and returns: is_default