code: function doRequest(endpoint, payload, params, callback) {
    debug('Calling API endpoint: ' + endpoint + '.');
  
    request
      .post(endpoint)
      .send({ payload: payload })
      .set('Accept', 'application/json')
      .end(function(err, res) {
        if ((!res || !res.body) && !err) {
          err = new Error('No response from server. ' +
            '(Hint: Have you mounted isomorphine.router() in your app?)');
        }
  
        if (err) {
          return handleError(err, params, callback);
        }
  
        var values = res.body.values;
  
        if (!values || values.constructor !== Array) {
          err = new Error('Fetched payload is not an array.');
          return handleError(err, params, callback);
        }
  
        debug('Resolving callback with ' + JSON.stringify(values, null, 3));
  
        // Sets the error argument to null
        values.unshift(null);
  
        callback.apply(this, values);
      });
  }
docs: Runs a request to an isomorphine's endpoint with the provided payload.
  
  @param  {String}   endpoint  The endpoint to request.
  @param  {Array}    payload   The arguments to send.
  @param  {Object}   params    The server's configuration and error handlers.
  @param  {Function} callback  The callback function to call afterwards.