'Solution'

app/cafe.py

@@ -0,0 +1,23 @@
+from datetime import date
+from app.errors import (
+    NotVaccinatedError,
+    OutdatedVaccineError,
+    NotWearingMaskError
+)
+
+
+class Cafe:
+
+    def __init__(self, name: str) -> None:
+        self.name = name
+
+    def visit_cafe(self, visitor: dict) -> str:
+        if "vaccine" not in visitor:
+            raise NotVaccinatedError("The visitor should be vaccinated.")
+        vaccine_expiration = visitor["vaccine"]["expiration_date"]
+        today = date.today()
+        if vaccine_expiration < today:
+            raise OutdatedVaccineError("Visitor's vaccine is outdated.")
+        if not visitor["wearing_a_mask"]:
+            raise NotWearingMaskError("All visitors should wear masks.")
+        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 +1,19 @@
-# write your code here
+from app.cafe import Cafe
+from app.errors import (
+    VaccineError,
+    NotWearingMaskError
+)
+
+
+def go_to_cafe(friends: list[dict], cafe: Cafe) -> str:
+    buy_mask = 0
+    for friend in friends:
+        try:
+            cafe.visit_cafe(friend)
+        except VaccineError:
+            return "All friends should be vaccinated"
+        except NotWearingMaskError:
+            buy_mask += 1
+    if buy_mask:
+        return f"Friends should buy {buy_mask} masks"
+    return f"Friends can go to {cafe.name}"