class_docstr: Specialty ParlAI parser used for the supercommand.
  
  Contains some special behavior.
class_docstr_tok: ["Specialty","ParlAI","parser","used","for","the","supercommand",".","Contains","some","special","behavior","."]
code: def add_extra_args(self, args):
      sa = [
          a
          for a in self._actions
          if isinstance(a, argparse._SubParsersAction)
      ]
      assert len(sa) == 1
      sa = sa[0]
      if args is None:
          args = sys.argv[1:]
      if args and args[0] in sa.choices:
          # if at all possible, try to use the actual subcommand only for
          # the add extra args, to prevent parse errors in other commands.
          sa.choices[args[0]].add_extra_args(args)
      else:
          for _, v in sa.choices.items():
              v.add_extra_args(args)
  
imports: import sys
  import io
  import argparse
  from typing import List, Optional, Dict, Any
  import parlai
  from parlai.core.opt import Opt
  from parlai.core.params import ParlaiParser, CustomHelpFormatter
  from abc import abstractmethod
  import importlib
  import pkgutil
  import parlai.scripts
  import parlai.utils.logging
  from parlai.core.loader import register_script, SCRIPT_REGISTRY
label_desc: Use image node_id 2 for calling the _SupercommandParser obj's underlying member method code with example usage: obj.add_extra_args(args) without return types