docs: def value(self):
          """Get parameter value.
  
          If this cached value is None and this serialized value is not None,
          calculate the new value from the serialized one.
  
          :return: parameter value.
          :raises: TypeError if serialized value is not an instance of self ptype
              . ParserError if parsing step raised an error.
          """
  
          result = self._value
  
          if result is None and self._svalue is not None:
  
              try:
                  result = self._value = self.resolve()
  
              except Exception as e:
                  reraise(
                      Parameter.Error,
                      Parameter.Error('Call the method "resolve" first.')
                  )
  
          return result