code: def test_defaults(self):
      heatmap = heatmap_layer(self.locations)
      state = heatmap.get_state()
      assert state["max_intensity"] is None
      assert state["opacity"] == 0.6
      assert state["point_radius"] is None
      assert state["dissipating"]
      assert state["gradient"] is None
  
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 7 for calling the HeatmapLayer obj's underlying member method code with example usage: obj.test_defaults() without return types