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/models/candidate.py

@@ -0,0 +1,34 @@
+from pip._vendor.packaging.version import parse as parse_version
+
+from pip._internal.models.link import Link
+from pip._internal.utils.models import KeyBasedCompareMixin
+
+
+class InstallationCandidate(KeyBasedCompareMixin):
+    """Represents a potential "candidate" for installation."""
+
+    __slots__ = ["name", "version", "link"]
+
+    def __init__(self, name: str, version: str, link: Link) -> None:
+        self.name = name
+        self.version = parse_version(version)
+        self.link = link
+
+        super().__init__(
+            key=(self.name, self.version, self.link),
+            defining_class=InstallationCandidate,
+        )
+
+    def __repr__(self) -> str:
+        return "<InstallationCandidate({!r}, {!r}, {!r})>".format(
+            self.name,
+            self.version,
+            self.link,
+        )
+
+    def __str__(self) -> str:
+        return "{!r} candidate (version {} at {})".format(
+            self.name,
+            self.version,
+            self.link,
+        )