Hi Jonathan,

 > I hope this is the right place for this.

absolutely. thanks.

 > Also, if #2 is an expression (i.e. 1+1), the calculation is not
 > performed correctly, since #2 (and #1) is not surrounded by ( and ).
 > (I am not sure if this can happen, or if the parameters are always
 > evaluated beforehand)

I haven't written that part and I'm not 100% sure about the intention here,
looks as normally the idea was to evaluate the parameters first. However,
either the documentation needs extending or one should safeguard against use
with expressions.

For the time being I have adopted Heiko's version (hopefully correctly) and
uploaded a new file