Node

A node is a basic unit of a data structure, such as a linked list or a tree. It typically contains some data and a reference to one or more other nodes. In a linked list, for example, each node contains a piece of data and a reference to the next node in the list. In a tree, each node contains a piece of data and references to its child nodes. Nodes are used to store and organize data in a way that allows for efficient access and manipulation.

```ts
const usersRef = db.collection('users').doc('alovelace');
const setAda = usersRef.set({
first: 'Ada',
last: 'Lovelace',
born: 1815
});
```