PrimaryExpression = Identifier | Literal
GroupedExpression = PrimaryExpression | `(` Expression `)`

UnaryOperator =  `-` | `!`
UnaryExpression = GroupedExpression | UnaryOperator UnaryExpression

MultiplyOperator = `*` | `/`
MultiplyExpression = UnaryExpression | MultiplyExpression MultiplyOperator UnaryExpression

AddOperator = `+` | `-`
AddExpression = MultiplyExpression | AddExpression AddOperator MultiplyExpression

AssignExpression = AddExpression | Identifier `=` AddExpression

Expression = AssignExpression