code: def test_tracker_host_port_from_cli__hostname_port__empty():
      input_str = ""
  
      actual_host, actual_port = tracker_host_port_from_cli(input_str)
  
      assert actual_host is None
      assert actual_port is None
  
imports: from tvm.driver.tvmc.tracker import tracker_host_port_from_cli
label_desc: Use image node_id 2 for calling a global function with example usage: test_tracker_host_port_from_cli__hostname_port__empty() without return types