docs: function _append(target, rules, isTargetEmpty){
    var concatedRules = [];
    var rulesContent;
    var l = rules.length;
    rules.forEach(function(rule, i){
      if(i < l - 1){
        concatedRules.push(rule + ',');
      }else{
        concatedRules.push(rule + '/*{{more}}*/');
      }
    });
  
    if(isTargetEmpty){
      rulesContent = EOL + concatedRules.join(EOL);
    }else{
      rulesContent = ',' + EOL + concatedRules.join(EOL);
    }
  
    return target.replace(/\/\*{{more}}\*\//, rulesContent);
  }