docs: function(file) {
      if (!AST.cache) {
        return;
      }
      else if (typeof file === 'string') {
        if (!AST.cache[file]) AST.cache[file] = null;
      }
      else if (file.isParsed() && !file.timestamp) {
        file.timestamp = Date.now();
        AST.cache[file.file] = file;
      }
    }