def METHOD_NAME(old_revision, new_revision, base_branch, token):
    '''Create a pull request. If a PR is already open for webrtc roller, do nothing.'''
    # Check if a pull request exists.
    # REST API ref: https://docs.github.com/en/rest/reference/pulls#list-pull-requests
    params = {'base': base_branch,
              'head': 'owt-bot:%s' % (TARGET_BRANCH), 'state': "open"}
    url = 'https://api.github.com/repos/open-webrtc-toolkit/owt-client-native/pulls'
    headers = {
        "Authorization": "token %s" % token,
        "Accept": "application/vnd.github.v3+json"
    }
    response = requests.get(url, params=params, headers=headers)
    if response.status_code != 200:
        print('Failed to get pull request list, REST response status code is %d.' % (
            response.status_code), file=sys.stderr)
        return -1
    fetched_prs = response.json()
    if len(fetched_prs) > 0:
        for METHOD_NAME in fetched_prs:
            if METHOD_NAME['user']['login'] == 'owt-bot':
                # Update existing PR.
                update_url = METHOD_NAME['url']
                print(update_url)
                update_params = {'title': commit_message(
                    old_revision, new_revision)}
                update_response = requests.patch(
                    update_url, json=update_params, headers=headers)
                print(json.dumps(update_params))
                if update_response.status_code != 200:
                    print(update_response.headers)
                    print(update_response.content)
                    print('Failed to update pull request, REST response status code is %d.' % (
                        update_response.status_code), file=sys.stderr)
                    return -1
                return 0
    # Create a new PR.
    create_params = {'title': commit_message(
        old_revision, new_revision), 'head': 'owt-bot:%s' % (TARGET_BRANCH), 'base': base_branch}
    create_response = requests.post(url, json=create_params, headers=headers)
    if create_response.status_code != 201:
        print('Failed to create pull request, REST response status code is %d.' % (
            create_response.status_code), file=sys.stderr)
        return -1
    return 0