Gets the value of a param in the user-supplied param map or its
        default value. Raises an error if neither is set.

def getOrDefault(self, param):
        """
        Gets the value of a param in the user-supplied param map or its
        default value. Raises an error if neither is set.
        """
        param = self._resolveParam(param)
        if param in self._paramMap:
            return self._paramMap[param]
        else:
            return self._defaultParamMap[param]