code: def single_subparser_possible(cmdlineargs, parser, completing):
      """Performs early analysis of the cmdline
  
      Looks at the first unparsed argument and if a known command,
      would return only that one.
  
      When a plain command invocation with `--version` is detected, it will be
      acted on directly (until sys.exit(0) to avoid wasting time on unnecessary
      further processing.
  
      Returns
      -------
      {'error', 'allknown', 'help', 'unknownopt', 'subcommand'}, None or str
          Returns a status label and a parameter for this status.
          'error': parsing failed, 'allknown': the parser successfully
          identified all arguments, 'help': a help request option was found,
          'unknownopt': an unknown or incomplete option was found,
          'subcommand': a potential subcommand name was found. For the latter
          two modes the second return value is the option or command name.
          For all other modes the second return value is None.
      """
      # Before doing anything additional and possibly expensive see may be that
      # we have got the command already
      try:
          parsed_args, unparsed_args = parser._parse_known_args(
              cmdlineargs[1:], argparse.Namespace()
          )
          # before anything handle possible datalad --version
          if not unparsed_args and getattr(
              parsed_args, "version", None
          ):
              parsed_args.version()  # will exit with 0
          if not (completing or unparsed_args):
              # there was nothing that could be a command
              fail_with_short_help(
                  parser,
                  msg="too few arguments, "
                  "run with --help or visit https://handbook.datalad.org",
                  exit_code=2,
              )
          lgr.debug(
              "Command line args 1st pass for DataLad %s. "
              "Parsed: %s Unparsed: %s",
              __version__,
              parsed_args,
              unparsed_args,
          )
      except Exception as exc:
          # this did not work out
          from datalad.support.exceptions import CapturedException
  
          ce = CapturedException(exc)
          lgr.debug("Early parsing failed with %s", ce)
          return "error", None
  
      if not unparsed_args:
          # cannot possibly be a subcommand
          return "allknown", None
  
      unparsed_arg = unparsed_args[0]
  
      # First unparsed could be either unknown option to top level "datalad"
      # or a command. Among unknown could be --help/--help-np which would
      # need to be dealt with
      if unparsed_arg in ("--help", "--help-np", "-h"):
          # not need to try to tune things, all these will result in everything
          # to be imported and parsed
          return "help", None
      elif unparsed_arg.startswith("-"):  # unknown or incomplete option
          if completing:
              return "unknownopt", unparsed_arg
          # will sys.exit
          fail_with_short_help(
              parser,
              msg=f"unrecognized argument {unparsed_arg}",
              # matches exit code of InsufficientArgumentsError
              exit_code=2,
          )
      else:  # potential command to handle
          return "subcommand", unparsed_arg
  
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 6 for calling a global function with example usage: single_subparser_possible(cmdlineargs, parser, completing) and returns: str,  None, str,  None, str,  None, str,  unparsed_arg, str,  unparsed_arg