code: def get_username():
      """
      Return the name of the current user, or None if the current user
      could not be determined.
      """
      from metaflow.metaflow_config import USER
  
      # note: the order of the list matters
      ENVVARS = ["SUDO_USER", "USERNAME", "USER"]
      for user in [USER] + [os.environ.get(x) for x in ENVVARS]:
          if user and user != "root":
              return user
      return None
  
imports: import os
  import shutil
  import sys
  import tempfile
  import zlib
  import base64
  from functools import wraps
  from io import BytesIO
  from itertools import takewhile
  import re
  from metaflow.exception import MetaflowUnknownUser, MetaflowInternalError
  from typing import NamedTuple
label_desc: Use image node_id 10 for calling a global function with example usage: get_username() and returns: None, user