把如下策略改成多頭策略，不做空

diff:=stkindi('','macd.diff',0,datatype);

diff_1:=stkindi('','macd.diff',0,datatype,-1);

if diff<diff_1 then begin

    sell(1,0,market);

    buyshort(holding=0,1,market);

end

if diff>diff_1 then begin

    sellshort(1,0,market);

    buy(holding=0,1,market);

end

diff:=stkindi('','macd.diff',0,datatype);

diff_1:=stkindi('','macd.diff',0,datatype,-1);

if diff<diff_1 then begin

    sell(1,0,market);

    buyshort(holding=0,1,market);

end

if diff>diff_1 then begin

    sellshort(1,0,market);

    buy(holding=0,1,market);

end

diff:=stkindi('','macd.diff',0,datatype);

diff_1:=stkindi('','macd.diff',0,datatype,-1);

if diff<diff_1 then begin

    sell(1,0,market);

    end

if diff>diff_1 then begin

        buy(holding=0,1,market);

end