class_docstr: Action class to append items to dict object.
  
  Examples:
      >>> parser = argparse.ArgumentParser()
      >>> _ = parser.add_argument('--conf', action=NestedDictAction,
      ...                         default={'a': 4})
      >>> parser.parse_args(['--conf', 'a=3', '--conf', 'c=4'])
      Namespace(conf={'a': 3, 'c': 4})
      >>> parser.parse_args(['--conf', 'c.d=4'])
      Namespace(conf={'a': 4, 'c': {'d': 4}})
      >>> parser.parse_args(['--conf', 'c.d=4', '--conf', 'c=2'])
      Namespace(conf={'a': 4, 'c': 2})
      >>> parser.parse_args(['--conf', '{d: 5, e: 9}'])
      Namespace(conf={'d': 5, 'e': 9})
code: def __init__(
      self,
      option_strings,
      dest,
      nargs=None,
      default=None,
      choices=None,
      required=False,
      help=None,
      metavar=None,
  ):
      super().__init__(
          option_strings=option_strings,
          dest=dest,
          nargs=nargs,
          default=copy.deepcopy(default),
          type=None,
          choices=choices,
          required=required,
          help=help,
          metavar=metavar,
      )
  
imports: import argparse
  import copy
  import yaml
label_desc: Use image node_id 1 to create a new NestedDictAction object from inherited base classes: argparse with example: obj = NestedDictAction(option_strings, dest, nargs, default, choices, required, help, metavar)