fix return type on gestformation

gestform.py

@@ -1,7 +1,7 @@
 #!/usr/bin/env python3
 # -*- coding: utf-8 -*-
 
-from typing import List
+from typing import List, Union
 from random import shuffle
 
 
@@ -24,7 +24,7 @@ def randomise_with_iterator(list_from: List[int]) -> int:
         yield randomized.pop()
 
 
-def gestformation(number: int) -> str:
+def gestformation(number: int) -> Union[str, int]:
     """Transform a number to a string depends on modularity"""
     if number % GESTE == 0 and number % FORME == 0:
         return "GestForm"