func intsSame(a, b Ints) bool {
	return reflect.ValueOf(a).Pointer() == reflect.ValueOf(b).Pointer()
}
intsSame determines whether two sets are backed by the same store. In the
current implementation using hash maps it makes use of the fact that
hash maps are passed as a pointer to a runtime Hmap struct. A map is
not seen by the runtime as a pointer though, so we use reflect to get
the maps' pointer values to compare.
package set
import "reflect"
func same(a, b Nodes) bool {
	return reflect.ValueOf(a).Pointer() == reflect.ValueOf(b).Pointer()
}