code: function(name, filter) {
  
          var data = {};
  
          // Call this method with only a filter function to define an unnamed filter.
          //
          //     this.addRequestFilter(function(options) {
          //       options.url = options.url + '/suffix';
          //       return options;
          //     });
          if (typeof(name) == 'function') {
            data = { filter: name };
  
          } else {
            this.removeRequestFilters(name);
            data = { name: name, filter: filter };
          }
  
          this.requestFilters.push(data);
        }
docs: <a name="method-addRequestFilter"></a> ### #addRequestFilter(name, filter) Adds a filter function to process options before an HTTP request is started. The filter function will be passed the complete request options and is expected to return the processed options.  this.addRequestFilter('signature', function(options) { options.headers = { 'X-Signature': sha1(options.method + options.url) }; return options; });