code: def test_vectorfield_line_width_op_update(self):
      vectorfield = HoloMap(
          {
              0: VectorField(
                  [(0, 0, 0, 1, 1), (0, 1, 0, 1, 4), (0, 2, 0, 1, 8)],
                  vdims=["A", "M", "line_width"],
              ),
              1: VectorField(
                  [(0, 0, 0, 1, 3), (0, 1, 0, 1, 2), (0, 2, 0, 1, 5)],
                  vdims=["A", "M", "line_width"],
              ),
          }
      ).opts(linewidth="line_width")
      plot = mpl_renderer.get_plot(vectorfield)
      artist = plot.handles["artist"]
      self.assertEqual(artist.get_linewidths(), [1, 4, 8])
      plot.update((1,))
      self.assertEqual(artist.get_linewidths(), [3, 2, 5])
  
file_path: holoviews/holoviews/tests/plotting/matplotlib/test_vectorfieldplot.py
imports: import numpy
  import pytest
  from holoviews.core.options import AbbreviatedException
  from holoviews.core.spaces import HoloMap
  from holoviews.element import VectorField
  from ..utils import ParamLogStream
  from .test_plot import TestMPLPlot, mpl_renderer
label_desc: Use image node_id 7 for calling the TestVectorFieldPlot obj's underlying member method code with example usage: obj.test_vectorfield_line_width_op_update() without return types