def METHOD_NAME(s):
    """
    Helper function to check whether a string is a valid identifier,
    as passed in on the command-line.
    """
    first = string.ascii_uppercase + '_'
    body = string.digits + first
    if not s:
        return False
    if s[0] not in first:
        return False
    if not all(c in body for c in s[1:]):
        return False
    return True