coal/helpers.go
func Require(m Model, flags ...string) {
	// check all flags
	for _, f := range flags {
		L(m, f, true)
	}
}
func Require(m Model, flags ...string) {
	// check all flags
	for _, f := range flags {
		L(m, f, true)
	}
}
// Require will check if the specified flags are set on the specified model and
// panic if one is missing.