code: def test_pair():
      p = pair(4, 0.9)
      assert p.first == 4
      assert p.second == 0.9
  
      p.first = 3
      p.second = 0.4
  
      assert p.first == 3
      assert p.second == 0.4
  
      assert str(p) == "3: 0.4"
      assert repr(p) == "dlib.pair(3, 0.4)"
  
      deser = pickle.loads(pickle.dumps(p, 2))
      assert deser.first == p.first
      assert deser.second == p.second
  
imports: from dlib import pair, make_sparse_vector, sparse_vector, sparse_vectors, sparse_vectorss
  from pytest import approx
label_desc: Use image node_id 1 for calling a global function with example usage: test_pair() without return types