code: def hr_dp990(self, value=None):
          
          if value is not None:
              try:
                  value = float(value)
              except ValueError:
                  raise ValueError('value {} need to be of type float '
                                   'for field `hr_dp990`'.format(value))
  
          self._hr_dp990 = value
docs: Corresponds to IDD Field `hr_dp990`
          humidity ratio, calculated at standard atmospheric pressure
          at elevation of station, corresponding to
          Dew-point temperature corresponding to 90.0% annual cumulative
          frequency of occurrence (cold conditions)
  
          Args:
              value (float): value for IDD Field `hr_dp990`
                  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