code: def add_parser(experiments_subparsers, parent_parser):
      EXPERIMENTS_BRANCH_HELP = "Promote an experiment to a Git branch."
      experiments_branch_parser = experiments_subparsers.add_parser(
          "branch",
          parents=[parent_parser],
          description=append_doc_link(
              EXPERIMENTS_BRANCH_HELP, "exp/branch"
          ),
          help=EXPERIMENTS_BRANCH_HELP,
          formatter_class=formatter.RawDescriptionHelpFormatter,
      )
      experiments_branch_parser.add_argument(
          "experiment", help="Experiment to be promoted."
      )
      experiments_branch_parser.add_argument(
          "branch",
          nargs="?",
          default=None,
          help=(
              "Optional name for the new Git branch. "
              "Defaults to '{experiment-name}-branch'."
          ),
      )
      experiments_branch_parser.set_defaults(func=CmdExperimentsBranch)
  
file_path: dvc/dvc/commands/experiments/branch.py
imports: from dvc.cli import formatter
  from dvc.cli.command import CmdBase
  from dvc.cli.utils import append_doc_link
  from dvc.log import logger
label_desc: Use image node_id 1 for calling a global function with example usage: add_parser(experiments_subparsers, parent_parser) without return types