code: def test_no_location_weighted(self):
      with self.assertRaises(traitlets.TraitError):
          heatmap_layer([], weights=[])
  
imports: import unittest
  import pytest
  import traitlets
  from ..heatmap import _HeatmapOptionsMixin, heatmap_layer, Heatmap, WeightedHeatmap
  from ..geotraitlets import InvalidPointException, InvalidWeightException
label_desc: Use image node_id 15 for calling the HeatmapLayer obj's underlying member method code with example usage: obj.test_no_location_weighted() without return types