def METHOD_NAME(filename):
    """
    Classify the file named by 'filename' and return the classification.
    If the file is classified as 'IT_Invalid' print an error message and exit
    the program.
    """
    ftype, msg = classify_input_file(filename)
    if ftype == IT_Invalid:
        print("Invalid input file: %s" % msg)
        sys.exit(1)
    return ftype