docs: function parseMwsResponse(method, headers, response, callback) {
    // if it's XML, then we an parse correctly
    if (headers && headers['content-type'] == 'text/xml') {
      xml2js.parseString(response, {explicitArray: false}, function(err, result) {
        if (err) {
          return callback(err);
        }
  
        if (result.ErrorResponse) {
          err = {
            Code: 'Unknown',
            Message: 'Unknown MWS error'
          };
  
          if (result.ErrorResponse.Error) {
            err = result.ErrorResponse.Error;
          }
  
          return callback(error.apiError(err.Code, err.Message, result));
        } else {
          callback(null, new Response(method, result));
        }
      });
    } else {
      callback(null, new Response(method, { "Response": response }));
    }
  }