solution

app/cafe.py

@@ -0,0 +1,25 @@
+from __future__ import annotations
+import datetime
+from app.errors import (
+    NotVaccinatedError,
+    NotWearingMaskError,
+    OutdatedVaccineError
+)
+
+
+class Cafe:
+    def __init__(self, name: str) -> None:
+        self.name = name
+
+    def visit_cafe(self, visitor: dict) -> str | Exception:
+        if "vaccine" not in visitor:
+            raise NotVaccinatedError("Not vaccinated!")
+
+        expiration_date = visitor["vaccine"].get("expiration_date")
+        if expiration_date and expiration_date < datetime.date.today():
+            raise OutdatedVaccineError("Outdated vaccine!")
+
+        if "wearing_a_mask" in visitor and not visitor["wearing_a_mask"]:
+            raise NotWearingMaskError("Not wearing a mask!")
+
+        return f"Welcome to {self.name}"

app/errors.py

@@ -0,0 +1,14 @@
+class VaccineError(Exception):
+    pass
+
+
+class NotVaccinatedError(VaccineError):
+    pass
+
+
+class OutdatedVaccineError(VaccineError):
+    pass
+
+
+class NotWearingMaskError(Exception):
+    pass

app/main.py

@@ -1 +1,16 @@
-# write your code here
+from app.errors import NotWearingMaskError, VaccineError
+from app.cafe import Cafe
+
+
+def go_to_cafe(friends: list[dict], cafe: Cafe) -> str:
+    masks_to_buy = 0
+    for friend in friends:
+        try:
+            cafe.visit_cafe(friend)
+        except VaccineError:
+            return "All friends should be vaccinated"
+        except NotWearingMaskError:
+            masks_to_buy += 1
+    if masks_to_buy > 0:
+        return f"Friends should buy {masks_to_buy} masks"
+    return f"Friends can go to {cafe.name}"