code: def _next_mutation(self):
          '''
          :return: True if mutated, False otherwise
          '''
          if self._keep_running():
              current_idx = self.model.current_index()
              self.session_info.current_index = current_idx
              next_idx = self._test_list.current()
              if next_idx is None:
                  return False
              skip = next_idx - current_idx - 1
              if skip > 0:
                  self.model.skip(skip)
              self._test_list.next()
              resp = self.model.mutate()
              return resp
          return Falsf _next_mutation(self):
          '''
          :return: True if mutated, False otherwise
          '''
          if self._keep_running():
              current_idx = self.model.current_index()
              self.session_info.current_index = current_idx
              next_idx = self._test_list.current()
              if next_idx is None:
                  return False
              skip = next_idx - current_idx - 1
              if skip > 0:
                  self.model.skip(skip)
              self._test_list.next()
              resp = self.model.mutate()
              return resp
          return False
docs: :return: True if mutated, False otherwise