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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 tick_length_pixels(pad, xaxis, yaxis, xlength, ylength=None):
 """ Set the axes tick lengths in pixels """

    if ylength is None:
        ylength = xlength
    xaxis.SetTickLength(xlength / float(pad.height_pixels))
    yaxis.SetTickLength(ylength / float(pad.width_pixels))