code: def test_vectorfield_line_width_op(self):
      vectorfield = VectorField(
          [(0, 0, 0, 1, 1), (0, 1, 0, 1, 4), (0, 2, 0, 1, 8)],
          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])
  
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 6 for calling the TestVectorFieldPlot obj's underlying member method code with example usage: obj.test_vectorfield_line_width_op() without return types