code: def test_discover_master(sentinel, master_ip):
      address = sentinel.discover_master("mymaster")
      assert address == (master_ip, 6379)
  
imports: import socket
  from unittest import mock
  import pytest
  import redis.sentinel
  from redis import exceptions
  from redis.sentinel import MasterNotFoundError, Sentinel, SentinelConnectionPool, SlaveNotFoundError
label_desc: Use image node_id 4 for calling a global function with example usage: test_discover_master(sentinel, master_ip) without return types