code: def test_point_size_op_update(self):
      points = HoloMap(
          {
              0: Points(
                  [(0, 0, 3), (0, 1, 1), (0, 2, 2)], vdims="size"
              ),
              1: Points(
                  [(0, 0, 2.5), (0, 1, 3), (0, 2, 1.2)], vdims="size"
              ),
          }
      ).opts(s="size")
      plot = mpl_renderer.get_plot(points)
      artist = plot.handles["artist"]
      self.assertEqual(artist.get_sizes(), np.array([3, 1, 2]))
      plot.update((1,))
      self.assertEqual(artist.get_sizes(), np.array([2.5, 3, 1.2]))
  
imports: import matplotlib.pyplot
  import numpy
  import pytest
  from holoviews.core.options import AbbreviatedException
  from holoviews.core.overlay import NdOverlay
  from holoviews.core.spaces import HoloMap
  from holoviews.element import Points
  from ..utils import ParamLogStream
  from .test_plot import TestMPLPlot, mpl_renderer
label_desc: Use image node_id 30 for calling the TestPointPlot obj's underlying member method code with example usage: obj.test_point_size_op_update() without return types