code: def data_period_start_day_of_week(self, value=None):
          
          if value is not None:
              try:
                  value = str(value)
              except ValueError:
                  raise ValueError(
                      'value {} need to be of type str '
                      'for field `data_period_start_day_of_week`'.format(value))
              if ',' in value:
                  raise ValueError('value should not contain a comma '
                                   'for field `data_period_start_day_of_week`')
              vals = set()
              vals.add("Sunday")
              vals.add("Monday")
              vals.add("Tuesday")
              vals.add("Wednesday")
              vals.add("Thursday")
              vals.add("Friday")
              vals.add("Saturday")
              if value not in vals:
                  raise ValueError(
                      'value {} is not an accepted value for '
                      'field `data_period_start_day_of_week`'.format(value))
  
          self._data_period_start_day_of_week = value
docs: Corresponds to IDD Field `data_period_start_day_of_week`
  
          Args:
              value (str): value for IDD Field `data_period_start_day_of_week`
                  Accepted values are:
                        - Sunday
                        - Monday
                        - Tuesday
                        - Wednesday
                        - Thursday
                        - Friday
                        - Saturday
                  if `value` is None it will not be checked against the
                  specification and is assumed to be a missing value
  
          Raises:
              ValueError: if `value` is not a valid value