code: def test_invalid_opacity(self):
      with self.assertRaises(traitlets.TraitError):
          Directions(self.start, self.end, stroke_opacity=20.0)
  
imports: import unittest
  import pytest
  import traitlets
  from ..directions import Directions, DEFAULT_STROKE_COLOR
label_desc: Use image node_id 17 for calling the DirectionsLayer obj's underlying member method code with example usage: obj.test_invalid_opacity() without return types