code: def _create_function(name, doc=""):
      
      def _(col):
          spark_ctx = SparkContext._active_spark_context
          java_ctx = (getattr(spark_ctx._jvm.com.sparklingpandas.functions,
                              name)
                      (col._java_ctx if isinstance(col, Column) else col))
          return Column(java_ctx)
      _.__name__ = name
      _.__doc__ = doc
      return _
docs: Create a function for aggregator by name