scale a value from one range to another

def scale(input_value, input_min, input_max, out_min, out_max):
    """ scale a value from one range to another
    """
    # Figure out how 'wide' each range is
    input_span = input_max - input_min
    output_span = out_max - out_min
    # Convert the left range into a 0-1 range (float)
    valuescaled = float(input_value - input_min) / float(input_span)
    # Convert the 0-1 range into a value in the right range.
    return out_min + (valuescaled * output_span)