code: def test_master_for(cluster, sentinel, master_ip):
      master = sentinel.master_for("mymaster", db=9)
      assert master.ping()
      assert master.connection_pool.master_address == (master_ip, 6379)
  
      # Use internal connection check
      master = sentinel.master_for(
          "mymaster", db=9, check_connection=True
      )
      assert master.ping()
  
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 13 for calling a global function with example usage: test_master_for(cluster, sentinel, master_ip) without return types