run approximate functions
    :param itf:
    :return:

def run(itf):
    """
    run approximate functions
    :param itf:
    :return:
    """

    if not itf:
        return 1

    # access user input
    options = SplitInput(itf)

    # read input
    print(" Reading input file ...")
    molecules = csv_interface.read_csv(os.path.abspath(options.inputpath), options)
    if not molecules:
        print("\n '{f} was unable to be parsed\n".format(f=os.path.basename(options.inputpath)))
        sys.exit(1)
    approximator(molecules, options)