code: def test_advance_left_recursion(self) -> None:
      grammar = """
          start: NUMBER | sign start
          sign: ['-']
          """
      self.assertEqual(
          self.calculate_first_sets(grammar),
          {"sign": {"'-'", ""}, "start": {"'-'", "NUMBER"}},
      )
  
imports: import unittest
  from test import test_tools
  from typing import Dict, Set
label_desc: Use image node_id 17 for calling the TestFirstSets obj's underlying member method code with example usage: obj.test_advance_left_recursion() without return types