code: def _required_run_dir():
      run_dir = os.getenv("RUN_DIR")
      if not run_dir:
          raise SystemExit(
              "missing required environment RUN_DIR for operation"
          )
      return run_dir
  
imports: import argparse
  import logging
  import os
  import subprocess
  import yaml
  from guild import op_util
  from guild import run
  from guild import run_manifest
  from guild import summary
  from guild import util
  from .None import dvc_util
label_desc: Use image node_id 2 for calling a global function with example usage: _required_run_dir() and returns: run_dir