function ( noPrune ) {
    var me = this;

    (!noPrune) && me._prune();
    writeJSON( me._pathToFile, me._persisted );
  }
function ( noPrune ) {
    var me = this;

    (!noPrune) && me._prune();
    writeJSON( me._pathToFile, me._persisted );
  }
function ( noPrune ) { var me = this ; ( ! noPrune ) && me . _prune ( ) ; writeJSON ( me . _pathToFile , me . _persisted ) ; }
Save the state of the cache identified by the docId to disk
as a JSON structure
@param [noPrune=false] {Boolean} whether to remove from cache the non visited files
@method save
Save the state of the cache identified by the docId to disk as a JSON structure