code: def test_empty_locations_stroke_color(self):
      symbols = symbol_layer([], stroke_color="red")
      assert symbols.markers == []
  
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 6 for calling the SymbolLayer obj's underlying member method code with example usage: obj.test_empty_locations_stroke_color() without return types