Add __hash__ method for models

Author: oschwald

geoip2/_internal.py

@@ -1,5 +1,6 @@
 """Internal utilities."""
 
+import json
 from abc import ABCMeta
 
 
@@ -12,6 +13,10 @@ def __eq__(self, other: object) -> bool:
     def __ne__(self, other: object) -> bool:
         return not self.__eq__(other)
 
+    def __hash__(self) -> int:
+        # This is not particularly efficient, but I don't expect it to be used much.
+        return hash(json.dumps(self.to_dict(), sort_keys=True))
+
     def to_dict(self) -> dict:  # noqa: C901, PLR0912
         """Return a dict of the object suitable for serialization."""
         result = {}