@classmethod
def get_cpu_thermal_rel(cls, session, server_key, sensor_name):
    """Get thermal relationships between CPU and a sensor 
        Args:
            session:  database session
            server_key(int): key of the server sensor belongs to
            sensor_name(str): name of the sensor affected by CPU load
        """
    results = session.run(
        """
            MATCH (:ServerWithBMC { key: $server })-[:HAS_SENSOR]->(sensor:Sensor { name: $sensor })
            MATCH (:CPU)<-[rel:HEATED_BY]-(sensor)
            RETURN rel
            """
        , server=server_key, sensor=sensor_name)
    record = results.single()
    return dict(record.get('rel')) if record else None
