Function add

add(
    this: GoodDB,
    key: string,
    value: number,
    options?: methodOptions,
): number | Promise<number>
Add a value to a key
Parameters
- this: GoodDB
- key: string
  The key to add the value to
- value: number
  The value to add
- Optionaloptions: methodOptions
  The options to use
Returns number | Promise<number>
A promise if the driver is async, otherwise a number
Example: Add a value to a key
Using the JSONDriver (sync)
```
const db = new GoodDB(new JSONDriver({
path: './database.json'
}));
db.add('key', 1);
```
Using the MongoDBDriver (async)
```
const db = new GoodDB(new MongoDBDriver({
uri: "..."
}));
await db.connect();
await db.add('key', 1);
```
- Defined in src/Methods/MathMethods.ts:33