code: def last(col, ignorenulls=False):
      
      sc = SparkContext._active_spark_context
      jc = sc._jvm.functions.last(_to_java_column(col), ignorenulls)
      return Column(jc)
docs: Aggregate function: returns the last value in a group.
  
      The function by default returns the last values it sees. It will return the last non-null
      value it sees when ignoreNulls is set to true. If all values are null, then null is returned.
  
      .. note:: The function is non-deterministic because its results depends on order of rows
          which may be non-deterministic after a shuffle.