class_docstr: Rendering engine parameter (no default).
docstr: The output formatter used for rendering
  (``'cairo'``, ``'gd'``, ...).
code: def formatter(self) -> typing.Optional[str]:
      """The output formatter used for rendering
      (``'cairo'``, ``'gd'``, ...)."""
      return self._formatter
  
file_path: graphviz/graphviz/parameters/formatters.py
imports: import typing
  from .None import base
label_desc: Use image node_id 3 for calling the Formatter obj's underlying member method code with example usage: obj.formatter() and returns: self