// precedence serves as "catch-all" precedence for selector,
// indexing, and other operator and delimiter tokens.
const (
	LowestPrec  = 0 // non-operators
	UnaryPrec   = 6
	HighestPrec = 7
)

// Precedence returns the operator precedence of the binary
// operator op. If op is not a binary operator, the result
// is LowestPrecedence.
func (op Token) Precedence() int {