code: def test_render_to_png(self):
      curve = Curve([])
      renderer = BokehRenderer.instance(fig="png")
      try:
          png, info = renderer(curve)
      except RuntimeError:
          raise SkipTest("Test requires selenium")
      self.assertIsInstance(png, bytes)
      self.assertEqual(info["file-ext"], "png")
  
imports: from io import BytesIO
  from unittest import SkipTest
  import numpy
  import panel
  import param
  from bokeh.io import curdoc
  from bokeh.themes.theme import Theme
  from panel.widgets import DiscreteSlider, FloatSlider, Player
  from pyviz_comms import CommManager
  from holoviews import Curve, DynamicMap, GridSpace, HoloMap, Image, Table
  from holoviews.element.comparison import ComparisonTestCase
  from holoviews.plotting import Renderer
  from holoviews.plotting.bokeh import BokehRenderer
  from holoviews.streams import Stream
label_desc: Use image node_id 12 for calling the BokehRendererTest obj's underlying member method code with example usage: obj.test_render_to_png() without return types