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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_trunc(format, timestamp):
 """ Returns timestamp truncated to the unit specified by the format. :param format: 'year', 'yyyy', 'yy', 'month', 'mon', 'mm', 'day', 'dd', 'hour', 'minute', 'second', 'week', 'quarter' [Row(year=datetime.datetime(1997, 1, 1, 0, 0))] [Row(month=datetime.datetime(1997, 2, 1, 0, 0))] """

    sc = SparkContext._active_spark_context
    return Column(sc._jvm.functions.date_trunc(format, _to_java_column(timestamp)))