code: def test_matrix_empty_init():
      m = matrix()
      assert m.nr() == 0
      assert m.nc() == 0
      assert m.shape == (0, 0)
      assert len(m) == 0
      assert repr(m) == "< dlib.matrix containing: >"
      assert str(m) == ""
  
file_path: dlib/tools/python/test/test_matrix.py
imports: from dlib import matrix
  from pytest import raises
label_desc: Use image node_id 1 for calling a global function with example usage: test_matrix_empty_init() without return types