FILE
	/usr/common/lib/exit.c

NAME
	can_pass - query whether somebody can pass through the exit

PROTOTYPE
	string can_pass(object user, object pass_through)

CALLED BY
	Anybody

DESCRIPTION
	This function should return a string reason why the user or mobile
	can't pass through, if they can't.  If they <i>can</i> pass
	through, it should return nil.

	If a non-user mobile is passing through, 'user' will be nil.  In
	any case, pass_through should be the body of the user or mobile
	attempting to pass through.

	The default implementation will check is_open to see if the exit
	is open, but do no other checking.

	This function isn't access-protected.  You should access-protect
	your version of this and all other inherited functions, including
	upgraded() and destructed().

RETURN VALUE
	The reason the mobile can't pass, or nil.

ERRORS
	Usually none.

SEE ALSO
	is_open, pass