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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 click_estimate_slope():
 """ Takes two clicks and returns the slope. Right-click aborts. """


    c1 = _pylab.ginput()
    if len(c1)==0:
        return None

    c2 = _pylab.ginput()
    if len(c2)==0:
        return None

    return (c1[0][1]-c2[0][1])/(c1[0][0]-c2[0][0])