Delete n objects from the stack
int SLdo_pop_n (unsigned int n)
The SLdo_pop_n function removes the top n objects from
the interpreter's run-time stack and frees all memory associated
with the objects. It returns zero upon success, or -1 upon
error (most likely due to a stack-underflow).
SLdo_pop, SLang_pop_integer, SLang_pop_string