code: function refresh ({accessToken, clientToken, selectedProfile}) {
    return fetch(`${YGGDRASIL_API}/refresh`, {
      method: 'POST',
      body: JSON.stringify({
        accessToken,
        clientToken,
        selectedProfile,
        requestUser: true
      }),
      headers: {
        'user-agent': USER_AGENT,
        'content-type': 'application/json',
        'accept': 'application/json'
      }
    })
      .then(handleErrors)
      .then(res => res.json())
  }
docs: Refreshes a given access token. May work on invalid access tokens (about 1 token back in time).
  
  @param {Object} session - a session access token
  @param {string} session.accessToken - a session access token
  @param {string=} session.clientToken - must match the one used to obtain the access token
  @param {Object=} session.selectedProfile - use only with access tokens that were **not** assigned a game profile
  @param {string} session.selectedProfile.id - profile UUID
  @param {string} session.selectedProfile.name - profile name (IGN)
  @returns {Promise<MojangSession>} resolves if Yggdrasil is feeling generous
  @see {@link http://wiki.vg/Authentication#Refresh}
  @example
  const session = await mojang.authenticate({username, password})
  // ...
  if (!await mojang.isValid(session)) {
  const nextSession = await mojang.refresh(session)
  // ...
  }