code: def test_layout_state(self):
      layout = Curve([1, 2, 3]) + Curve([2, 4, 6])
      state = self._get_plot_state(layout)
      self.assertEqual(state["data"][0]["y"], np.array([1, 2, 3]))
      self.assertEqual(state["data"][0]["yaxis"], "y")
      self.assertEqual(state["data"][1]["y"], np.array([2, 4, 6]))
      self.assertEqual(state["data"][1]["yaxis"], "y2")
  
file_path: holoviews/holoviews/tests/plotting/plotly/test_layoutplot.py
imports: import numpy
  from holoviews.element import Curve, Image
  from .test_plot import TestPlotlyPlot, plotly_renderer
label_desc: Use image node_id 3 for calling the TestLayoutPlot obj's underlying member method code with example usage: obj.test_layout_state() without return types