Function add_hook:
Defined in module hooks (file: /std/object/hooks.c)

add_hook(string tag, function hook) sets up the function 'hook' to be
called whenever call_hooks(tag, ...) is done.  Note that if you want
to remove the tag later, you have to do so with the _exact_ same function
pointer.

e.g.

function my_hook = (: my_hook_func :);

 add_hook("foo", my_hook);

 remove_hook("foo", my_hook);


Prototype:
void add_hook(string tag, function hook);
