SYNOPSIS
int referencep(mixed arg)
DESCRIPTION
returns true if arg was passed by reference to the current
function, instead of the usual call-by-value.
Note that arg has to be passed by reference to the efun,
a.g. referencep(&x).
SEE ALSO
references(LPC) clonep(E), closurep(E), floatp(E),
mappingp(E), objectp(E), intp(E), pointerp(E), stringp(E),
symbolp(E), structp(E)