code: function revoke (req, res, next) {
    var provider = providers[req.params.provider]
    var endpoint = provider && provider.endpoints && provider.endpoints.revoke
  
    if (!provider) {
      return next(new InvalidRequestError('Unknown provider'))
    }
  
    if (!endpoint) {
      return next(new InvalidRequestError('Undefined revoke endpoint'))
    }
  
    User.get(req.claims.sub, function (err, user) {
      if (err) {
        return next(err)
      }
  
      if (!user) {
        return next(new InvalidRequestError('Unknown user'))
      }
  
      if (!user.providers[req.params.provider]) {
        return next(new InvalidRequestError('No provider for this user'))
      }
  
      var auth = user.providers[req.params.provider].auth
      var url = endpoint.url
      var method = endpoint.method.toLowerCase()
      var param = endpoint.auth && endpoint.auth.param
      var token = auth && auth.access_token
  
      request[method](url)
        .query(param + '=' + token)
        .end(function (err, response) {
          res.json({
            err: err,
            response: response
          })
        })
    })
  }
docs: Revoke