class_docstr: Stores some state that persists between recursions into the element tree
code: def __contains__(self, key: int):
      return key in self._element_diagram_states
  
imports: import railroad
  import pyparsing
  import typing
  from typing import List, NamedTuple, Generic, TypeVar, Dict, Callable, Set, Iterable
  from jinja2 import Template
  from io import StringIO
  import inspect
label_desc: Use image node_id 5 for calling the ConverterState obj's underlying member method code with example usage: obj.__contains__(key) and returns: unknown