code: def flush(self):
      self.context.flush_commands()
  
file_path: vispy/vispy/app/backends/tests/test_offscreen_util.py
imports: from vispy.app.backends._offscreen_util import OffscreenContext, FrameBufferHelper
  from vispy.testing import run_tests_if_main, requires_application
  from vispy import gloo
  import numpy
label_desc: Use image node_id 2 for calling the FakeCanvas obj's underlying member method code with example usage: obj.flush() without return types