[amibroker] First and Last Trading Day in Month

[Patrick]

I want to testing buying and selling based on months. Using the very simple 
forumla below will not work (month end mainly) if there is no trading day on 
the 28th. 

Is there a way to write to code... "Buy on the first trading day of the month, 
and sell on the last trading day of the month" ??


MO = 1;
Buy = (Month() == MO) AND(Day() = 1 );
Sell = (Month() == MO) AND (Day() = 28);