fixup! Add type annotations

CADETProcess/processModel/componentSystem.py

@@ -162,7 +162,7 @@ def density(self) -> list[float | None]:
         return [spec.density for spec in self.species]
 
     def __str__(self) -> str:
-        """String representation of the component."""
+        """str: String representation of the component."""
         return self.name
 
     def __iter__(self):
@@ -432,11 +432,13 @@ def densities(self) -> list[float | None]:
         return densities
 
     def __repr__(self) -> str:
+        """str: Representation of the system by class name and component names."""
         return f'{self.__class__.__name__}({self.names})'
 
     def __iter__(self):
+        """Iterator over components in the system."""
         yield from self.components
 
     def __getitem__(self, item: int) -> Component:
+        """Component: Retrieve a component by its index."""
         return self._components[item]
-