code: def test_optional_before(self) -> None:
      grammar = """
          start: term NEWLINE
          term: ['+'] NUMBER
          """
      self.assertEqual(
          self.calculate_first_sets(grammar),
          {"term": {"NUMBER", "'+'"}, "start": {"NUMBER", "'+'"}},
      )
  
imports: import unittest
  from test import test_tools
  from typing import Dict, Set
label_desc: Use image node_id 8 for calling the TestFirstSets obj's underlying member method code with example usage: obj.test_optional_before() without return types