nl_tokens: Remove keys that were not accessed / set since the last time the prune method was called .
pl_tokens: function ( ) { var me = this ; var obj = { } ; var keys = Object . keys ( me . _visited ) ; // no keys visited for either get or set value if ( keys . length === 0 ) { return ; } keys . forEach ( function ( <mask> ) { obj [ key ] = me . _persisted [ key ] ; } ) ; me . _visited = { } ; me . _persisted = obj ; }