code: def repeat(col, n):
      
      sc = SparkContext._active_spark_context
      return Column(sc._jvm.functions.repeat(_to_java_column(col), n))
docs: Repeats a string column n times, and returns it as a new string column.
  
      >>> df = spark.createDataFrame([('ab',)], ['s',])
      >>> df.select(repeat(df.s, 3).alias('s')).collect()
      [Row(s=u'ababab')]