angularjs's annotate(fn) extracted and ported to underscore

gistfile1.js

/**
 * Parse a constructor's signature to find out the names of his arguments. This
 * is central to AngularJS dependency injection mechanism.
 */
function annotate(fn) {
    var $inject, fnText, argDecl, last;
 
    if (typeof fn == 'function') {
      if (!($inject = fn.$inject)) {
        $inject = [];
        fnText = fn.toString().replace(STRIP_COMMENTS, '');
        argDecl = fnText.match(FN_ARGS);
        _.forEach(argDecl[1].split(FN_ARG_SPLIT), function(arg) {
          arg.replace(FN_ARG, function(all, underscore, name) {
            $inject.push(name);
          });
        });
        fn.$inject = $inject;
      }
    } else if (_.isArray(fn)) {
      last = fn.length - 1;
      //assertArgFn(fn[last], 'fn')
      $inject = fn.slice(0, last);
    } else {
      //assertArgFn(fn, 'fn', true);
    }
    return $inject;
  }

supporting blog: http://www.dustingetz.com/2013/05/13/javascript-dependency-injection-angularjs-style.html