def METHOD_NAME(self) -> None:
    grammar = """
    start: expr NEWLINE
    expr: !'a' opt
    opt: 'a' | 'b' | 'c'
    """
    self.assertEqual(self.calculate_first_sets(grammar), {
        "opt": {"'b'", "'a'", "'c'"},
        "expr": {"'b'", "'c'"},
        "start": {"'b'", "'c'"},
    })