code: def filter(self, data):
          
          if isinstance(data, list):
              result = []
              for d in data:
                  result.append(Instances(javabridge.static_call(
                      "Lweka/filters/Filter;", "useFilter",
                      "(Lweka/core/Instances;Lweka/filters/Filter;)Lweka/core/Instances;",
                      d.jobject, self.jobject)))
              return result
          else:
              return Instances(javabridge.static_call(
                  "Lweka/filters/Filter;", "useFilter",
                  "(Lweka/core/Instances;Lweka/filters/Filter;)Lweka/core/Instances;",
                  data.jobject, self.jobject))
docs: Filters the dataset(s). When providing a list, this can be used to create compatible train/test sets,
          since the filter only gets initialized with the first dataset and all subsequent datasets get transformed
          using the same setup.
  
          NB: inputformat(Instances) must have been called beforehand.
  
          :param data: the Instances to filter
          :type data: Instances or list of Instances
          :return: the filtered Instances object(s)
          :rtype: Instances or list of Instances