code: function (sig, fn) {
          var isArr = toType(fn) === 'array';
          sig || (sig = []);
  
          map[sig.join('::').toLowerCase()] = {
            fn: isArr ? passObject(fn) : fn,
            inject: isArr ? true : (fn.length > sig.length)
          };
  
          return this;
        }
docs: add a new method