code: def visibility(self, value=9999.0):
          
          if value is not None:
              try:
                  value = float(value)
              except ValueError:
                  raise ValueError('value {} need to be of type float '
                                   'for field `visibility`'.format(value))
  
          self._visibility = value
docs: Corresponds to IDD Field `visibility` This is the value for
          visibility in km. (Horizontal visibility at the time indicated.)
  
          Args:
              value (float): value for IDD Field `visibility`
                  Unit: km
                  Missing value: 9999.0
                  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