1. PostgreSQL copy of all MySQL created and tested.\n 2. Purchase Orders and Sales Orders and stock level management added to MySQL, PostgreSQL, and server and front end code.

env_test/Lib/site-packages/pip/_internal/utils/models.py

@@ -0,0 +1,39 @@
+"""Utilities for defining models
+"""
+
+import operator
+from typing import Any, Callable, Type
+
+
+class KeyBasedCompareMixin:
+    """Provides comparison capabilities that is based on a key"""
+
+    __slots__ = ["_compare_key", "_defining_class"]
+
+    def __init__(self, key: Any, defining_class: Type["KeyBasedCompareMixin"]) -> None:
+        self._compare_key = key
+        self._defining_class = defining_class
+
+    def __hash__(self) -> int:
+        return hash(self._compare_key)
+
+    def __lt__(self, other: Any) -> bool:
+        return self._compare(other, operator.__lt__)
+
+    def __le__(self, other: Any) -> bool:
+        return self._compare(other, operator.__le__)
+
+    def __gt__(self, other: Any) -> bool:
+        return self._compare(other, operator.__gt__)
+
+    def __ge__(self, other: Any) -> bool:
+        return self._compare(other, operator.__ge__)
+
+    def __eq__(self, other: Any) -> bool:
+        return self._compare(other, operator.__eq__)
+
+    def _compare(self, other: Any, method: Callable[[Any, Any], bool]) -> bool:
+        if not isinstance(other, self._defining_class):
+            return NotImplemented
+
+        return method(self._compare_key, other._compare_key)