completed the basic ui and anilist module

app/Model/base_model.py

@@ -0,0 +1,33 @@
+# The model implements the observer pattern. This means that the class must
+# support adding, removing, and alerting observers. In this case, the model is
+# completely independent of controllers and views. It is important that all
+# registered observers implement a specific method that will be called by the
+# model when they are notified (in this case, it is the `model_is_changed`
+# method). For this, observers must be descendants of an abstract class,
+# inheriting which, the `model_is_changed` method must be overridden.
+
+
+class BaseScreenModel:
+    """Implements a base class for model modules."""
+
+    _observers = []
+
+    def add_observer(self, observer) -> None:
+        self._observers.append(observer)
+
+    def remove_observer(self, observer) -> None:
+        self._observers.remove(observer)
+
+    def notify_observers(self, name_screen: str) -> None:
+        """
+        Method that will be called by the observer when the model data changes.
+
+        :param name_screen:
+            name of the view for which the method should be called
+            :meth:`model_is_changed`.
+        """
+
+        for observer in self._observers:
+            if observer.name == name_screen:
+                observer.model_is_changed()
+                break