func(r rune) bool {
		return r != utf8.RuneError
	},
	"IsValidRune",
}

type TrimFuncTest struct {
	f        predicate
	in       string
	trimOut  []byte
	leftOut  []byte
	rightOut []byte
}

func not(p predicate) predicate {
	return predicate{
		func(r rune) bool {
			return !p.f(r)
		},
		"not " + p.name,
	}
}