code: def test_vectorss_extend():
      vss = vectorss()
      vss.extend([generate_test_vectors(), generate_test_vectors()])
      assert len(vss) == 2
  
imports: from dlib import vector, vectors, vectorss, dot
  from pytest import raises
label_desc: Use image node_id 20 for calling a global function with example usage: test_vectorss_extend() without return types