Solution2

app/main.py

@@ -1,41 +1,36 @@
 class SoftwareEngineer:
-    skills = []
-
     def __init__(self, name: str) -> None:
         self.name = name
+        self.skills = []
 
-    @classmethod
-    def learn_skill(cls, skill: str) -> None:
-        return cls.skills.append(skill)
+    def learn_skill(self, skill: str) -> None:
+        return self.skills.append(skill)
 
 
 class FrontendDeveloper(SoftwareEngineer):
-    skills = ["JavaScript", "HTML", "CSS"]
-
     def __init__(self, name: str) -> None:
         super().__init__(name)
+        self.skills = ["JavaScript", "HTML", "CSS"]
 
     def create_awesome_web_page(self) -> str:
         print(f"{self.name} is creating a webpage...")
         return "<h1>Hello world</h1>"
 
 
 class BackendDeveloper(SoftwareEngineer):
-    skills = ["Python", "SQL", "Django"]
-
     def __init__(self, name: str) -> None:
         super().__init__(name)
+        self.skills = ["Python", "SQL", "Django"]
 
     def create_powerful_api(self) -> str:
         print(f"{self.name} is creating an API...")
         return "http://127.0.0.1:8000"
 
 
 class AndroidDeveloper(SoftwareEngineer):
-    skills = ["Java", "Android studio"]
-
     def __init__(self, name: str) -> None:
         super().__init__(name)
+        self.skills = ["Java", "Android studio"]
 
     def create_smooth_mobile_app(self) -> str:
         print(f"{self.name} is creating a mobile app...")
@@ -47,10 +42,13 @@ class FullStackDeveloper(
     FrontendDeveloper,
     SoftwareEngineer
 ):
-    skills = BackendDeveloper.skills + FrontendDeveloper.skills
 
     def __init__(self, name: str) -> None:
         super().__init__(name)
+        self.skills = (
+            BackendDeveloper(self.name).skills
+            + FrontendDeveloper(self.name).skills
+        )
 
     def create_web_application(self) -> None:
         print(f"{self.name} started creating a web application...")