function extend(dst) {
  forEach(arguments, function(obj){
    if (obj !== dst) {
      forEach(obj, function(value, key){
        dst[key] = value;
      });
    }
  });
  return dst;
}
@ngdoc function
@name angular.extend
@function

@description
Extends the destination object `dst` by copying all of the properties from the `src` object(s)
to `dst`. You can specify multiple `src` objects.

@param {Object} dst Destination object.
@param {...Object} src Source object(s).