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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 constantLine(requestContext, value):
 """ Takes a float F. Draws a horizontal line at value F across the graph. Example:: &target=constantLine(123.456) """

    name = "constantLine(%s)" % str(value)
    start = int(epoch(requestContext['startTime']))
    end = int(epoch(requestContext['endTime']))
    step = int((end - start) / 2.0)
    series = TimeSeries(str(value), start, end, step, [value, value, value])
    series.pathExpression = name
    return [series]