model.provider: Add AbstractObjectStore.get() method

aas/model/provider.py

@@ -40,6 +40,19 @@ class AbstractObjectProvider(metaclass=abc.ABCMeta):
         """
         pass
 
+    def get(self, identifier: Identifier, default: Optional[Identifiable] = None) -> Optional[Identifiable]:
+        """
+        Find an object in this set by its identification, with fallback parameter
+
+        :param default: An object to be returned, if no object with the given identification is found
+        :return: The Identifiable object with the given identification in the provider. Otherwise the `default` object
+                 or None, if none is given.
+        """
+        try:
+            return self.get_identifiable(identifier)
+        except KeyError:
+            return default
+
 
 _IT = TypeVar('_IT', bound=Identifiable)