How to get SNMPv3 by python with auth no priv?

Question

如何通过 python 使用 auth no priv 获取 SNMPv3？ 我尝试用 pysnmp 来做，但它不起作用。 设备：交换机 CISCO 2960

from pysnmp.hlapi import UsmUserData, usmHMACSHAAuthProtocol,usmAesCfb256Protocol
from pysnmp.hlapi import SnmpEngine, UdpTransportTarget, ContextData,ObjectType, ObjectIdentity, getCmd

snmpName =username
snmpPass = password
ipHost = ipAddress

auth=UsmUserData(userName=snmpName,authKey=snmpPass,authProtocol=usmHMACSHAAuthProtocol,privKey='',privProtocol=usmAesCfb256Protocol)


data = getCmd(SnmpEngine(),auth,UdpTransportTarget((ipHost, 161)),ContextData(),ObjectType(ObjectIdentity('SNMPv2-MIB', 'sysName', 0)))

errorIndication, errorStatus, errorIndex, varBinds = next(iterator)
print(errorIndication, errorStatus, errorIndex, varBinds)

当我尝试以任何方式打印此数据时出现错误