get_sort_key as tuple

Author: mmatera

pymathics/graph/__main__.py

@@ -461,7 +461,7 @@ def get_sort_key(self, pattern_sort=False):
         if pattern_sort:
             return super(Graph, self).get_sort_key(True)
         else:
-            return hash(self)
+            return (1, 3, Symbol("Pymathics`Graph"), tuple(), 2, len(self.pixels), hash(self))
 
     @property
     def value(self):