From bd58442912cf13e7f3795821e2c13edf5e23aed1 Mon Sep 17 00:00:00 2001
From: Salvo 'LtWorf' Tomaselli <tiposchi@tiscali.it>
Date: Wed, 12 Aug 2020 15:20:29 +0200
Subject: [PATCH] Make hash raise an error

---
 relational/relation.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/relational/relation.py b/relational/relation.py
index 346730d..84782dd 100644
--- a/relational/relation.py
+++ b/relational/relation.py
@@ -52,7 +52,8 @@ class Relation:
     An empty relation needs a header, and can be filled using the insert()
     method.
     '''
-    __hash__ = None #  type: None
+    def __hash__(self):
+        raise NotImplementedError()
 
     def __init__(self, filename: Optional[Union[str, Path]] = None) -> None:
         self._readonly = False