code: function(_attr, _filter, _filterParam, _chain) {
  
              if(typeof _filter === 'string') {
                var filter = $filter(_filter);
                _filter = function(_value) { return filter(_value, _filterParam); };
              }
  
              decoders[_attr] = _chain ? Utils.chain(decoders[_attr], _filter) : _filter;
              return this;
            }
docs: @memberof BuilderApi#
  
  @description Assigns a decoding function/filter to a given attribute.
  
  @param {string} _name Attribute name
  @param {string|function} _filter filter or function to register
  @param {mixed} _filterParam Misc filter parameter
  @param {boolean} _chain If true, filter is chained to the current attribute filter.
  @return {BuilderApi} self