input: Write a python function to check if the given arguments length is 0, and raise a CommandError if true.
  assert handle() == CommandError("I need at least one argument.")
  assert handle('myscript.py') == None
  assert handle('myscript.py', 'arg1') == None
output: def handle(*args):
      if len(args) == 0:
          raise CommandError("I need at least one argument.")
      return None
  
  class CommandError(Exception):
      pass