code: def copy_instances(cls, dataset, from_row=None, num_rows=None):
          
          if from_row is None or num_rows is None:
              return Instances(
                  javabridge.make_instance(
                      "weka/core/Instances", "(Lweka/core/Instances;)V",
                      dataset.jobject))
          else:
              dataset = cls.copy_instances(dataset)
              return Instances(
                  javabridge.make_instance(
                      "weka/core/Instances", "(Lweka/core/Instances;II)V",
                      dataset.jobject, from_row, num_rows))
docs: Creates a copy of the Instances. If either from_row or num_rows are None, then all of
          the data is being copied.
  
          :param dataset: the original dataset
          :type dataset: Instances
          :param from_row: the 0-based start index of the rows to copy
          :type from_row: int
          :param num_rows: the number of rows to copy
          :type num_rows: int
          :return: the copy of the data
          :rtype: Instances