Optional parameters in functions

["Richard van Zon" <rvanzon@xxxxxxxxxxxx>]

Hi,

I am busy embedding S-Lang into my program, and I need a method to use
optional parameters to my functions. Like :

int add_a_to_b_and_maybe_c(int *a, int *b, [int *c])

where a and b are required and c is optional....the function will skip c if
it's not set and just adds a to b...
Is this possible and did I miss some lines in the docs or how can I realize
this ?
Thanks in advance,

Richard van Zon.