code: function _extend(obj, from) {
          for ( let key in from ) if ( hop.call(from, key) ) {
              obj[key] = from[key];
          }
          return obj;
      }
docs: Copy properties to `obj` from `from`
  
  @param  (Object) obj
  @param  (Object) from - source object
  
  @return (Object) obj
  @api private