code: def test_defaults(self):
      symbol = Symbol(self.location)
      state = symbol.get_state()
      assert state["fill_color"] is None
      assert state["fill_opacity"] == 1.0
      assert state["stroke_color"] is None
      assert state["stroke_opacity"] == 1.0
      assert state["scale"] == 4
  
imports: import unittest
  import pytest
  import numpy
  import traitlets
  from ..marker import MarkerOptions, Marker, Markers, Symbol, marker_layer, symbol_layer
label_desc: Use image node_id 2 for calling the SymbolTest obj's underlying member method code with example usage: obj.test_defaults() without return types