string signalOP(int period1 , int period2 , ENUM_MA_METHOD mode=MODE_EMA )
  {
   double buffer_ma1[],buffer_ma2[];

   int handle_ma1=iMA(_Symbol,time,period1,0,mode,PRICE_CLOSE);
   ArraySetAsSeries(buffer_ma1,true);
   CopyBuffer(handle_ma1,0,0,3,buffer_ma1);

   int handle_ma2=iMA(_Symbol,time,period2,0,mode,PRICE_CLOSE);
   ArraySetAsSeries(buffer_ma2,true);
   CopyBuffer(handle_ma2,0,0,3,buffer_ma2);

   if(buffer_ma1[2]<=buffer_ma2[2]&& buffer_ma1[1]>buffer_ma2[1])
      return "buy";
   else
      if(buffer_ma1[2]>=buffer_ma2[2]&&buffer_ma1[1]<buffer_ma2[1])
         return "sell";
      else
         return "no signal";
  }' );