fix import

examples/Hilbert.py

@@ -1,7 +1,12 @@
 """
 Test whether we can reproduce Hilbert curves
 """
+#!/usr/bin/env python3
+
 import sys
+import numpy as np
 
 sys.path.append("..")
-from despace import sort_coordinates as sc
+from despace.spatial_sort import SortND
+
+# TO DO