<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def single_node_env(args):
 """Sets up environment for a single-node TF session. Args: :args: command line arguments as either argparse args or argv list """

  # setup ARGV for the TF process
  if isinstance(args, list):
      sys.argv = args
  elif args.argv:
      sys.argv = args.argv

  # setup ENV for Hadoop-compatibility and/or GPU allocation
  num_gpus = args.num_gpus if 'num_gpus' in args else 1
  util.single_node_env(num_gpus)