code: function extend( to, from ){
          var desc, key;
          for ( key in from ){
              desc = Object.getOwnPropertyDescriptor( from, key );
              if ( desc.get || desc.set ){
  
                  Object.defineProperty( to, key, desc );
  
              } else if ( Physics.util.isFunction( desc.value ) ){
  
                  to[ key ] = desc.value;
              }
          }
          return to;
      }
docs: extend that supports getters/setters only extends functions