code: def test_slicing(self):
      p = ggplot(data, aes("x", "y"))
  
      _lyrs = self.lyrs[1:]
      assert isinstance(_lyrs, Layers)
  
      p1 = p + self.lyrs[0] + self.lyrs[2]
      assert _get_colors(p1) == colors[::2]
  
      p2 = p + self.lyrs[::2]
      assert _get_colors(p2) == colors[::2]
  
      p3 = p + (self.lyrs[:1] + self.lyrs[2:])
      assert _get_colors(p3) == colors[::2]
  
file_path: plotnine/tests/test_layers.py
imports: from pathlib import Path
  import numpy
  import pandas
  import pytest
  from plotnine import aes, geom_path, geom_point, ggplot
  from plotnine.exceptions import PlotnineError, PlotnineWarning
  from plotnine.layer import Layers, layer
label_desc: Use image node_id 2 for calling the TestLayers obj's underlying member method code with example usage: obj.test_slicing() without return types