('integer_literal', r'\d+'),
('symbol', r'[a-z_]+'),
('single_quoted_string_literal', r"'.*?'"),
+ ('double_quoted_string_literal', r'".*?"'),
('comparison_level_operator', r'(<=|>=|==|!=|<|>)'),
('assignment_operator', r'='),
('addition_level_operator', r'(\+\+|\+|-)'),