code: def decode(col, charset):
      
      sc = SparkContext._active_spark_context
      return Column(sc._jvm.functions.decode(_to_java_column(col), charset))
docs: Computes the first argument into a string from a binary using the provided character set
      (one of 'US-ASCII', 'ISO-8859-1', 'UTF-8', 'UTF-16BE', 'UTF-16LE', 'UTF-16').