code: function(item) {
          var getter, args;
          if (item.block) {
              getter = 'block';
              args = [item.block];
              if (item.elem) {
                  getter = 'elem';
                  args.push(item.elem);
              }
              if (item.mod) {
                  getter += '-mod';
                  args.push(item.mod);
                  if (item.val) {
                      getter += '-val';
                      args.push(item.val);
                  }
              }
              return this.getRel(getter, args);
          }
          return '';
      }
docs: Get relative to level directory path prefix on the filesystem
  to specified BEM entity described as an object with special
  properties.
  
  @param {Object} item  BEM entity object.
  @param {String} item.block  Block name.
  @param {String} item.elem   Element name.
  @param {String} item.mod    Modifier name.
  @param {String} item.val    Modifier value.
  @return {String}  Relative path prefix.