Gets a required component reference that matches specified locator.

         :param locator: the locator to find a reference by.

         :return: a matching component reference.

         :raises: a [[ReferenceException]] when no references found.

def get_one_required(self, locator):
        """
         Gets a required component reference that matches specified locator.

         :param locator: the locator to find a reference by.

         :return: a matching component reference.

         :raises: a [[ReferenceException]] when no references found.
         """
        components = self.find(locator, True)
        return components[0] if len(components) > 0 else None