code: def test_hex_tile_alpha_op(self):
      hextiles = HexTiles(np.random.randn(1000, 2)).opts(alpha="Count")
      plot = bokeh_renderer.get_plot(hextiles)
      glyph = plot.handles["glyph"]
      self.assertEqual(
          property_to_dict(glyph.fill_alpha), {"field": "alpha"}
      )
  
imports: import numpy
  from holoviews.core import Dimension
  from holoviews.element import HexTiles
  from holoviews.plotting.bokeh.hex_tiles import hex_binning
  from holoviews.plotting.bokeh.util import property_to_dict
  from .test_plot import TestBokehPlot, bokeh_renderer
label_desc: Use image node_id 11 for calling the TestHexTilesPlot obj's underlying member method code with example usage: obj.test_hex_tile_alpha_op() without return types