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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def file_name_error(file_name):
 """File name error This method checks if the input file name is valid. Parameters file_name : str File name string Raises ------ IOError If file name not specified or file not found """


    if file_name == '' or file_name[0][0] == '-':
        raise IOError('Input file name not specified.')

    elif not os.path.isfile(file_name):
        raise IOError('Input file name [%s] not found!' % file_name)