class_docstr: A cache structure that maps Pygments Tokens to :class:`.Attr`.
  (This is an important speed up.)
class_docstr_tok: ["A","cache","structure","that","maps","Pygments","Tokens","to",":","class",":","`",".Attr","`",".","(","This","is","an","important","speed","up",".",")"]
code: def __missing__(self, token):
      try:
          result = self.get_style_for_token(token)
      except KeyError:
          result = None
  
      self[token] = result
      return result
  
imports: from __future__ import unicode_literals
  from prompt_toolkit.filters import to_cli_filter
  from prompt_toolkit.layout.mouse_handlers import MouseHandlers
  from prompt_toolkit.layout.screen import Point, Screen, WritePosition
  from prompt_toolkit.output import Output
  from prompt_toolkit.styles import Style
  from prompt_toolkit.token import Token
  from prompt_toolkit.utils import is_windows
  from six.moves import range
label_desc: Use image node_id 2 for calling the _TokenToAttrsCache obj's underlying member method code with example usage: obj.__missing__(token) and returns: result