src/sage/combinat/necklace.py: Add missing import

Author: Matthias Koeppe

src/sage/combinat/necklace.py

@@ -26,8 +26,9 @@
 from sage.categories.finite_enumerated_sets import FiniteEnumeratedSets
 from sage.combinat.composition import Composition
 from sage.combinat.misc import DoublyLinkedList
-from sage.rings.integer import Integer
 from sage.misc.misc_c import prod
+from sage.rings.integer import Integer
+from sage.rings.integer_ring import ZZ
 from sage.structure.parent import Parent
 from sage.structure.unique_representation import UniqueRepresentation