def _CompletionsFromArgs(fn_args):
  """Takes a list of fn args and returns a list of the fn's completion strings.

  Args:
    fn_args: A list of the args accepted by a function.
  Returns:
    A list of possible completion strings for that function.
  """
  completions = []
  for arg in fn_args:
    arg = arg.replace('_', '-')
    completions.append('--{arg}'.format(arg=arg))
  return completions