docs: function set(key, value /*, exflag, secs, pxflag, ms, xflag, req*/) {
    var i
      , arg
      // expiry flag: EX | PX
      , flag
      // expiry value: number
      , expiry
      // exists flag: NX | XX
      , xflag
      // request object when available
      , req;
  
    for(i = 0;i < arguments.length;i++) {
      arg = arguments[i];
      if(typeof arg === 'object') {
        req = arg;
      }else if(arg === Constants.NX || arg === Constants.XX) {
        xflag = arg;
      }else if(arg === Constants.EX || arg === Constants.PX) {
        flag = arg;
        expiry = arguments[++i];
      }
    }
    return this.setKey(key, value, flag, expiry, xflag, req) || null;
  }