add apostrophes for more readability

pyiron_workflow/mixin/semantics.py

@@ -200,12 +200,12 @@ def __getattr__(self, key):
             return self._children[key]
         except KeyError:
             # Raise an attribute error from getattr to make sure hasattr works well!
-            msg = f"Could not find attribute {key} on {self.label} "
+            msg = f"Could not find attribute '{key}' on {self.label} "
             msg += f"({self.__class__.__name__}) or among its children "
             msg += f"({self._children.keys()})."
             matches = get_close_matches(key, self._children.keys(), cutoff=0.8)
             if len(matches) > 0:
-                msg += f" Did you mean {matches[0]} and not {key}?"
+                msg += f" Did you mean '{matches[0]}' and not '{key}'?"
             raise AttributeError(msg)
 
     def __iter__(self):

tests/unit/mixin/test_semantics.py

@@ -18,7 +18,7 @@ def test_getattr(self):
         with self.assertRaises(AttributeError) as context:
             _ = self.middle1.Middle_sub
         self.assertIn(
-            "Did you mean middle_sub and not Middle_sub",
+            "Did you mean 'middle_sub' and not 'Middle_sub'",
             str(context.exception),
             msg="middle_sub must be suggested as it is close to Middle_sub"
         )