Fixing issue with NewType.

Author: tscrim

src/sage/combinat/plane_partition.py

@@ -44,8 +44,6 @@
 from sage.sets.family import Family
 from sage.sets.non_negative_integers import NonNegativeIntegers
 
-PP = NewType('PP', 'PlanePartition')
-
 
 @richcmp_method
 class PlanePartition(ClonableArray,
@@ -1170,6 +1168,9 @@ def bounding_box(self):
         return (len(self), len(self[0]), self[0][0])
 
 
+PP = NewType('PP', PlanePartition)
+
+
 class PlanePartitions(UniqueRepresentation, Parent):
     r"""
     Plane partitions.