Add cmp() function

python/plugins/processing/algs/qgis/voronoi.py

@@ -896,3 +896,12 @@ if __name__ == "__main__":
 
     sl = SiteList(pts)
     voronoi(sl, c)
+
+def cmp(a, b):
+    """Compare the two objects x and y and return an integer according to the
+    outcome. The return value is negative if x < y, zero if x == y and strictly
+    positive if x > y.
+
+    In python 2 cmp() was a built in function but in python 3 is gone.
+    """
+    return (a > b) - (a < b)