type Path interface {
	// GetKey returns the key of the path.
	GetKey() []byte

	// GetValue returns the value of the path, or nil if it is not set.
	GetValue() []byte

	// GetRoot returns the store root calculated from the key. It should match
	// the tree root for the path to be valid.
	GetRoot() []byte
}

type StagingTree interface {
	Tree

	// WithTx decorates the staging tree to use a transaction to perform
	// operations on the database while using the same underlying data.
	WithTx(store.Transaction) StagingTree

	// Commit writes the tree to a persistent storage.
	Commit() error
}

type Tree interface {
	store.Readable

	// GetRoot returns the root hash of this tree.
	GetRoot() []byte

	// GetPath returns a path to a key and its value in the tree. It can be used
	// as a proof of inclusion or a proof of absence in the contrary.
	GetPath(key []byte) (Path, error)

	// Stage must create a writable tree from the current one that will be
	// passed to the callback, then return it.
	Stage(func(store.Snapshot) error) (StagingTree, error)
}