SYNOPSIS
	mixed * intersect_alist(mixed * list1, mixed * list2)

DESCRIPTION
	Does a fast set intersection on alists. The operator '&' does
	set intersection on arrays in general.

EXAMPLE
	new_alist=intersect_alist(alist1, alist2);

SEE ALSO
	filter_array(E), assoc(E), insert_alist(E), map_array(E),
	member_array(E), order_alist(E), sort_array(E), unique_array(E)
