code: def test_vector_custom():
      v_a = m.VectorEl()
      v_a.append(m.El(1))
      v_a.append(m.El(2))
      assert str(v_a) == "VectorEl[El{1}, El{2}]"
  
      vv_a = m.VectorVectorEl()
      vv_a.append(v_a)
      vv_b = vv_a[0]
      assert str(vv_b) == "VectorEl[El{1}, El{2}]"
  
file_path: coremltools/deps/pybind11/tests/test_stl_binders.py
imports: import pytest
  from pybind11_tests import stl_binders
label_desc: Use image node_id 5 for calling a global function with example usage: test_vector_custom() without return types