## ParserBuilder.prefix() method [​](/content/docs/sdk/core.parserbuilder.prefix#parserbuilderprefix-method/index.html)

**Signature:**

```typescript
prefix(tokenType: string, precedence: number, builder: (token: Token, right: Atom) => Atom): this;
```

## Parameters [​](/content/docs/sdk/core.parserbuilder.prefix#parameters/index.html)

| Parameter   | Type     | Description |
| ----------- | -------- | ----------- |
| tokenType   | string   |             |
| precedence  | number   |             |
| builder     | (token: [Token](/content/docs/sdk/core.token), right: [Atom](/content/docs/sdk/core.atom)) => [Atom](/content/docs/sdk/core.atom) |             |

**Returns:**

this

- [ParserBuilder.prefix() method](/content/docs/sdk/core.parserbuilder.prefix#parserbuilderprefix-method/index.html)
- [Parameters](/content/docs/sdk/core.parserbuilder.prefix#parameters/index.html)