code: def get_error(self, startingPercentage=0.0, endPercentage=100.0, startDate=None, endDate=None):
          
          # not initialized:
          if len(self._errorValues) == 0:
              raise StandardError("The last call of initialize(...) was not successfull.")
  
          # check for wrong parameters
          if not (0.0 <= startingPercentage <= 100.0):
              raise ValueError("startingPercentage has to be in [0.0, 100.0].")
          if not (0.0 <= endPercentage <= 100.0):
              raise ValueError("endPercentage has to be in [0.0, 100.0].")
          if endPercentage < startingPercentage:
              raise ValueError("endPercentage has to be greater or equal than startingPercentage.")
  
          return self._calculate(startingPercentage, endPercentage, startDate, endDate)
docs: Calculates the error for the given interval (startingPercentage, endPercentage) between the TimeSeries
          given during :py:meth:`BaseErrorMeasure.initialize`.
  
          :param float startingPercentage: Defines the start of the interval. This has to be a value in [0.0, 100.0].
              It represents the value, where the error calculation should be started.
              25.0 for example means that the first 25% of all calculated errors will be ignored.
          :param float endPercentage:    Defines the end of the interval. This has to be a value in [0.0, 100.0].
              It represents the value, after which all error values will be ignored. 90.0 for example means that
              the last 10% of all local errors will be ignored.
          :param float startDate: Epoch representing the start date used for error calculation.
          :param float endDate: Epoch representing the end date used in the error calculation.
  
          :return:    Returns a float representing the error.
          :rtype: float
  
          :raise:    Raises a :py:exc:`ValueError` in one of the following cases:
  
              - startingPercentage not in [0.0, 100.0]
              - endPercentage      not in [0.0, 100.0]
              - endPercentage < startingPercentage
  
          :raise:    Raises a :py:exc:`StandardError` if :py:meth:`BaseErrorMeasure.initialize` was not successfull before.