Initial

advent/days/template.py

@@ -0,0 +1,23 @@
+import typing
+
+ResultType = int | str | list[str]
+
+
+class Day(typing.Protocol):
+    day_num: int
+
+    @staticmethod
+    def part1(lines: typing.Iterator[str]) -> ResultType | None:
+        ...
+
+    @staticmethod
+    def part2(lines: typing.Iterator[str]) -> ResultType | None:
+        ...
+
+
+def is_day(object: typing.Any) -> typing.TypeGuard[Day]:
+    try:
+        return (isinstance(object.day_num, int)
+                and callable(object.part1) and callable(object.part2))
+    except AttributeError:
+        return False