def METHOD_NAME(file_name):
    if file_name is None:
        return "file name should not be null."
    if not os.path.exists(file_name):
        return file_name + " file doesn't exist."
    if not os.path.isfile(file_name):
        return file_name + " is not a file."
    if os.path.getsize(file_name) % 4:
        return "file size error, not a standard float data bin file."
    return