class_docstr: Class for forecasting time series with mean 
code: def _window(self, time_series: np.ndarray):
      return max(
          2, round(time_series.shape[0] * self.part_for_averaging)
      )
  
imports: from copy import copy
  import numpy
  from fedot.core.data.data import InputData, OutputData
  from fedot.core.operations.evaluation.operation_implementations.data_operations.ts_transformations import ts_to_table, transform_features_and_target_into_lagged
  from fedot.core.operations.evaluation.operation_implementations.implementation_interfaces import ModelImplementation
  from fedot.core.operations.operation_parameters import OperationParameters
  from fedot.core.repository.dataset_types import DataTypesEnum
label_desc: Use image node_id 6 for calling the NaiveAverageForecastImplementation obj's underlying member method code with example usage: obj._window(time_series) and returns: max