code: def assert_vline(self, shape, x, xref="x", ydomain=(0, 1)):
      self.assertEqual(shape["type"], "line")
      self.assertEqual(shape["x0"], x)
      self.assertEqual(shape["x1"], x)
      self.assertEqual(shape["xref"], xref)
  
      self.assertEqual(shape["y0"], ydomain[0])
      self.assertEqual(shape["y1"], ydomain[1])
      self.assertEqual(shape["yref"], "paper")
  
imports: import numpy
  from holoviews.element import Bounds, Box, HLine, Path, Rectangles, Segments, Tiles, VLine
  from .test_plot import TestPlotlyPlot
label_desc: Use image node_id 1 for calling the TestVLineHLine obj's underlying member method code with example usage: obj.assert_vline(shape, x, xref, ydomain) without return types