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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 date_add(start, days):
 """ Returns the date that is `days` days after `start` [Row(next_date=datetime.date(2015, 4, 9))] """

    sc = SparkContext._active_spark_context
    return Column(sc._jvm.functions.date_add(_to_java_column(start), days))