code: def test_empty_markers_symbol():
      markers = Markers()
      markers.symbol = "o"
  
file_path: vispy/vispy/visuals/tests/test_markers.py
imports: import numpy
  import pytest
  from vispy.scene.visuals import Markers
  from vispy.testing import requires_application, TestingCanvas, run_tests_if_main
  from vispy.testing.image_tester import assert_image_approved
label_desc: Use image node_id 3 for calling a global function with example usage: test_empty_markers_symbol() without return types