code: def _amend_param_parser_kwargs_for_help(
      parser_kwargs, param, default=None
  ):
      if "metavar" not in parser_kwargs and isinstance(
          param.constraints, EnsureChoice
      ):
          parser_kwargs["metavar"] = "{%s}" % "|".join(
              # don't use short_description(), because
              # it also needs to give valid output for
              # Python syntax (quotes...), but here we
              # can simplify to shell syntax where everything
              # is a string
              p
              for p in param.constraints._allowed
              # in the cmdline None pretty much means
              # don't give the options, so listing it
              # doesn't make sense. Moreover, any non-string
              # value cannot be given and very likely only
              # serves a special purpose in the Python API
              # or implementation details
              if isinstance(p, str)
          )
      help = alter_interface_docs_for_cmdline(param._doc)
      if help:
          help = help.rstrip()
          if help[-1] != ".":
              help += "."
          if param.constraints is not None:
              help += _get_help_for_parameter_constraint(param)
      if default is not None and not parser_kwargs.get(
          "action", ""
      ).startswith("store_"):
          # if it is a flag, in commandline it makes little sense to show
          # showing the Default: (likely boolean).
          # See https://github.com/datalad/datalad/issues/3203
          help += " [Default: %r]" % (default,)
      return help
  
imports: import argparse
  import logging
  import sys
  from collections import defaultdict
  from functools import partial
  from datalad import __version__
  from datalad.interface.base import get_cmd_doc, get_interface_groups, is_api_arg, load_interface
  from datalad.support.constraints import EnsureChoice
  from datalad.utils import getargspec
  from .common_args import common_args
  from .exec import call_from_parser
  from .helpers import get_commands_from_groups
  from .interface import alter_interface_docs_for_cmdline, get_cmd_ex, get_cmdline_command_name
label_desc: Use image node_id 4 for calling a global function with example usage: _amend_param_parser_kwargs_for_help(parser_kwargs, param, default) and returns: help