api.go
func (da *Cedar) Get(key []byte) (value int, err error) {
	to, err := da.Jump(key, 0)
	if err != nil {
		return 0, err
	}
	return da.Value(to)
}
func (da *Cedar) Get(key []byte) (value int, err error) {
	to, err := da.Jump(key, 0)
	if err != nil {
		return 0, err
	}
	return da.Value(to)
}
// Get returns the value associated with the given `key`.
// It is equivalent to
//		id, err1 = Jump(key)
//		value, err2 = Value(id)
// Thus, it may return ErrNoPath or ErrNoValue,