code: def test_pop_empty_gl_state():
      node = vispy.visuals.MeshVisual()
      assert node._prev_gl_state == []
      og_gl_state = node._vshare.gl_state.copy()
      node.pop_gl_state()
      assert node._vshare.gl_state == og_gl_state
  
file_path: vispy/vispy/scene/tests/test_visuals.py
imports: import pytest
  from vispy.scene import visuals, Node
  from vispy.scene.visuals import VisualNode
  import vispy.visuals
label_desc: Use image node_id 5 for calling a global function with example usage: test_pop_empty_gl_state() without return types