code: def add_subparser(
      _intfspec, subparsers, cmd_name, formatter_class, completing=False
  ):
      """Given an interface spec, add a subparser to subparsers under cmd_name"""
      _intf = load_interface(_intfspec)
      if _intf is None:
          # failed to load, error was already logged
          return
  
      # compose argparse.add_parser() arguments, focused on docs
      parser_args = dict(formatter_class=formatter_class)
      # use class description, if no explicit description is available
      intf_doc = get_cmd_doc(_intf)
      if not completing:
          parser_args["description"] = alter_interface_docs_for_cmdline(
              intf_doc
          )
          if hasattr(_intf, "_examples_"):
              intf_ex = alter_interface_docs_for_cmdline(
                  get_cmd_ex(_intf)
              )
              parser_args["description"] += intf_ex
  
      # create the sub-parser
      subparser = subparsers.add_parser(
          cmd_name, add_help=False, **parser_args
      )
      # our own custom help for all commands, we must do it here
      # (not in setup_parser_for_interface()) because the top-level parser must
      # not unconditionally have it available initially
      parser_add_common_opt(subparser, "help")
      # let module configure the parser
      setup_parser_for_interface(
          subparser, _intf, completing=completing
      )
      # and we would add custom handler for --version
      parser_add_version_opt(
          subparser,
          _intf.__module__.split(".", 1)[0],
          include_name=True,
      )
      # logger for command
      # configure 'run' function for this command
      plumbing_args = dict(
          # this is the key execution handler
          func=partial(call_from_parser, _intf),
          # use the logger of the module that defined the interface
          logger=logging.getLogger(_intf.__module__),
          subparser=subparser,
      )
      if hasattr(_intf, "result_renderer_cmdline"):
          plumbing_args[
              "result_renderer"
          ] = _intf.result_renderer_cmdline
      subparser.set_defaults(**plumbing_args)
      return subparser
  
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 8 for calling a global function with example usage: add_subparser(_intfspec, subparsers, cmd_name, formatter_class, completing) and returns: subparser