Create example for how to create a challenge using whiteAccessToken and blackAccessToken

challengeUser.js

export async function challengeUser(
  whiteAccessToken: string,
  blackAccessToken: string,
  username: string
): Promise<ChallengeGame> {
  const response = await createClient(whiteAccessToken).post<
    CreateChallengeResponse
  >(
    `/api/challenge/${username}`,
    stringify({
      acceptByToken: blackAccessToken,
      rated: 'false',
      'clock.limit': 60,
      'clock.increment': 0,
      color: 'white',
    }),
    {
      headers: {
        'Content-Type': 'application/x-www-form-urlencoded',
      },
    }
  );
  return response.data.game;
}

Players can generate tokens via https://lichess.org/account/oauth/token/create then give those tokens to the tournament organizer.