@classmethod
def get_psu_sensor_names(cls, session, server_key, psu_num):
    """Retrieve server-specific psu sensor names
        Args:
            session:  database session
            server_key(int): key of the server sensors belongs to
            psu_num(int): psu num
        """
    query = []
    sensor_match = (
        'MATCH (:PSU {{ key: {} }})<-[:HAS_COMPONENT]-(:Asset)-[:HAS_SENSOR]->(sensor {{ num: {} }})'
        )
    label_match = map('sensor:{}'.format, ['psuCurrent', 'psuTemperature',
        'psuStatus', 'psuPower'])
    query.extend([sensor_match.format(server_key, psu_num), 'WHERE {}'.
        format(' or '.join(label_match)), 'RETURN sensor'])
    results = session.run('\n'.join(query))
    psu_names = {}
    for record in results:
        entry = dict(record.get('sensor'))
        psu_names[entry['type']] = entry['name']
    return psu_names
