code: def testGradientPalette(self):
      gp = GradientPalette("red", "blue", 3)
      self.assertTrue(gp.get(0) == (1.0, 0.0, 0.0, 1.0))
      self.assertTrue(gp.get(1) == (0.5, 0.0, 0.5, 1.0))
      self.assertTrue(gp.get(2) == (0.0, 0.0, 1.0, 1.0))
  
imports: import unittest
  from igraph import hsv_to_rgb, hsva_to_rgba, hsl_to_rgb, hsla_to_rgba, rgb_to_hsl, rgba_to_hsla, rgba_to_hsva, rgb_to_hsv, GradientPalette, AdvancedGradientPalette
label_desc: Use image node_id 1 for calling the PaletteTests obj's underlying member method code with example usage: obj.testGradientPalette() without return types