Help needed conversion of Metastock indicator

[valnie]

Can anyone help to convert the following Metastock codes to EFS please?

EMA1:= Mov(CLOSE,13,E);
EMA2:= Mov(EMA1,13,E);
Difference:= EMA1-EMA2;
LagEMA13:= EMA1 + Difference;
EMA1:= Mov(CLOSE,21,E);
EMA2:= Mov(EMA1,21,E);
Difference:= EMA1 - EMA2;
LagEMA21:= EMA1 + Difference;
LagMA:=LagEMA13 - LagEMA21;
LagMA

Tried using Formula wizard but it does not seems to allow me to add the difference back to EMA1.

Many thanks in advance...