code: def test_optional_after(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 7 for calling the TestFirstSets obj's underlying member method code with example usage: obj.test_optional_after() without return types