Example
user = db.labels.create("User")
u1 = db.nodes.create(name="user1")
user.add(u1)
u2 = db.nodes.create(name="user2")
user.add(u2)
You can associate a label with many nodes in one go
Language = db.labels.create("Language")
b1 = db.nodes.create(name="C++")
b2 = db.nodes.create(name="Python")
beer.add(b1, b2)
