switch v.Kind() {
	case reflect.Invalid:
		return false
	case reflect.Pointer:
		return !v.IsNil()
	}
	return true
}

// encodeSingle encodes a single top-level non-struct value.
func (enc *Encoder) encodeSingle(b *encBuffer, engine *encEngine, value reflect.Value) {
	state := enc.newEncoderState(b)
	defer enc.freeEncoderState(state)
	state.fieldnum = singletonField