pullRequest(object) {
        const payload = this.payload;
        return Object.assign({
            // @ts-ignore - this.payload may not have `issue` or `pull_request` keys
            pull_number: (payload.issue || payload.pull_request || payload).number,
        }, this.repo(object));
    }
Return the `owner`, `repo`, and `pull_number` params for making API requests
against a pull request. The object passed in will be merged with the repo params.


```js
const params = context.pullRequest({body: 'Hello World!'})
// Returns: {owner: 'username', repo: 'reponame', pull_number: 123, body: 'Hello World!'}
```

@param object - Params to be merged with the pull request params.