diff --git a/masque/abstract.py b/masque/abstract.py
index 3301c66..9eefcbb 100644
--- a/masque/abstract.py
+++ b/masque/abstract.py
@@ -45,7 +45,7 @@ class Abstract(PortList):
 #    def build(
 #            self,
 #            library: 'MutableLibrary',
-#            tools: None | 'Tool' | MutableMapping[str | None, 'Tool'] = None,
+#            tools: 'None | Tool | MutableMapping[str | None, Tool]' = None,
 #            ) -> 'Builder':
 #        """
 #        Begin building a new device around an instance of the current device
diff --git a/masque/library.py b/masque/library.py
index 781983a..c2cd9b4 100644
--- a/masque/library.py
+++ b/masque/library.py
@@ -219,7 +219,7 @@ class Library(Mapping[str, 'Pattern'], metaclass=ABCMeta):
         if isinstance(tops, str):
             tops = (tops,)
 
-        flattened: dict[str, 'Pattern' | None] = {}
+        flattened: dict[str, 'Pattern | None'] = {}
 
         def flatten_single(name) -> None:
             flattened[name] = None
@@ -342,7 +342,7 @@ class Library(Mapping[str, 'Pattern'], metaclass=ABCMeta):
             current_pattern = visit_after(current_pattern, **visit_args)
             ```
           where `visit_args` are
-            `hierarchy`:  (top_pattern_or_None, L1_pattern, L2_pattern, ..., parent_pattern)
+            `hierarchy`:  (top_pattern_or_None, L1_pattern, L2_pattern, ..., parent_pattern, target_pattern)
                           tuple of all parent-and-higher pattern names. Top pattern name may be
                           `None` if not provided in first call to .dfs()
             `transform`:  numpy.ndarray containing cumulative
@@ -413,7 +413,7 @@ class Library(Mapping[str, 'Pattern'], metaclass=ABCMeta):
             pattern = visit_after(pattern, hierarchy=hierarchy, memo=memo, transform=transform)
 
         if pattern is not original_pattern:
-            name = hierarchy[-1]
+            name = hierarchy[-1]            # TODO what is name=None?
             if not isinstance(self, MutableLibrary):
                 raise LibraryError('visit_* functions returned a new `Pattern` object'
                                    ' but the library is immutable')
@@ -431,14 +431,14 @@ class MutableLibrary(Library, MutableMapping[str, 'Pattern'], metaclass=ABCMeta)
     #def __getitem__(self, key: str) -> 'Pattern':
     #def __iter__(self) -> Iterator[str]:
     #def __len__(self) -> int:
-    #def __setitem__(self, key: str, value: 'Pattern' | Callable[[], 'Pattern']) -> None:
+    #def __setitem__(self, key: str, value: 'Pattern | Callable[[], Pattern]') -> None:
     #def __delitem__(self, key: str) -> None:
 
     @abstractmethod
     def __setitem__(
             self,
             key: str,
-            value: 'Pattern' | Callable[[], 'Pattern'],
+            value: 'Pattern | Callable[[], Pattern]',
             ) -> None:
         pass
 
@@ -858,7 +858,7 @@ class WrapLibrary(MutableLibrary):
     def __setitem__(
             self,
             key: str,
-            value: 'Pattern' | Callable[[], 'Pattern'],
+            value: 'Pattern | Callable[[], Pattern]',
             ) -> None:
         if key in self.mapping:
             raise LibraryError(f'"{key}" already exists in the library. Overwriting is not allowed!')
@@ -898,7 +898,7 @@ class LazyLibrary(MutableLibrary):
     def __setitem__(
             self,
             key: str,
-            value: 'Pattern' | Callable[[], 'Pattern'],
+            value: 'Pattern | Callable[[], Pattern]',
             ) -> None:
         if key in self.mapping:
             raise LibraryError(f'"{key}" already exists in the library. Overwriting is not allowed!')
@@ -1045,7 +1045,7 @@ class Tree(MutableLibrary):
 
     def __init__(
             self,
-            top: str | 'NamedPattern',
+            top: 'str | NamedPattern',
             library: MutableLibrary | None = None
             ) -> None:
         self.top = top if isinstance(top, str) else top.name
@@ -1068,7 +1068,7 @@ class Tree(MutableLibrary):
     def __len__(self) -> int:
         return len(self.library)
 
-    def __setitem__(self, key: str, value: 'Pattern' | Callable[[], 'Pattern']) -> None:
+    def __setitem__(self, key: str, value: 'Pattern | Callable[[], Pattern]') -> None:
         self.library[key] = value
 
     def __delitem__(self, key: str) -> None:
diff --git a/masque/pattern.py b/masque/pattern.py
index 9e3afa1..8c2ea7c 100644
--- a/masque/pattern.py
+++ b/masque/pattern.py
@@ -601,7 +601,7 @@ class Pattern(PortList, AnnotatableImpl, Mirrorable):
         Returns:
             self
         """
-        flattened: dict[str | None, 'Pattern' | None] = {}
+        flattened: dict[str | None, 'Pattern | None'] = {}
 
         # TODO both Library and Pattern have flatten()... pattern is in-place?
         def flatten_single(name: str | None) -> None:
diff --git a/masque/ref.py b/masque/ref.py
index 17fddb1..69b40e4 100644
--- a/masque/ref.py
+++ b/masque/ref.py
@@ -46,7 +46,7 @@ class Ref(
 
     def __init__(
             self,
-            target: str | 'NamedPattern' | None,
+            target: 'str | NamedPattern | None',
             *,
             offset: ArrayLike = (0.0, 0.0),
             rotation: float = 0.0,
@@ -120,7 +120,7 @@ class Ref(
     def as_pattern(
             self,
             *,
-            pattern: 'Pattern' | None = None,
+            pattern: 'Pattern | None' = None,
             library: Mapping[str, 'Pattern'] | None = None,
             ) -> 'Pattern':
         """
@@ -177,7 +177,7 @@ class Ref(
     def get_bounds(
             self,
             *,
-            pattern: 'Pattern' | None = None,
+            pattern: 'Pattern | None' = None,
             library: Mapping[str, 'Pattern'] | None = None,
             ) -> NDArray[numpy.float64] | None:
         """
diff --git a/masque/traits/repeatable.py b/masque/traits/repeatable.py
index 7be1559..492e270 100644
--- a/masque/traits/repeatable.py
+++ b/masque/traits/repeatable.py
@@ -22,7 +22,7 @@ class Repeatable(metaclass=ABCMeta):
     '''
     @property
     @abstractmethod
-    def repetition(self) -> 'Repetition' | None:
+    def repetition(self) -> 'Repetition | None':
         """
         Repetition object, or None (single instance only)
         """
@@ -30,14 +30,14 @@ class Repeatable(metaclass=ABCMeta):
 
 #    @repetition.setter
 #    @abstractmethod
-#    def repetition(self, repetition: 'Repetition' | None):
+#    def repetition(self, repetition: 'Repetition | None'):
 #        pass
 
     '''
     ---- Methods
     '''
     @abstractmethod
-    def set_repetition(self, repetition: 'Repetition' | None) -> Self:
+    def set_repetition(self, repetition: 'Repetition | None') -> Self:
         """
         Set the repetition
 
@@ -56,18 +56,18 @@ class RepeatableImpl(Repeatable, metaclass=ABCMeta):
     """
     __slots__ = _empty_slots
 
-    _repetition: 'Repetition' | None
+    _repetition: 'Repetition | None'
     """ Repetition object, or None (single instance only) """
 
     '''
     ---- Non-abstract properties
     '''
     @property
-    def repetition(self) -> 'Repetition' | None:
+    def repetition(self) -> 'Repetition | None':
         return self._repetition
 
     @repetition.setter
-    def repetition(self, repetition: 'Repetition' | None):
+    def repetition(self, repetition: 'Repetition | None'):
         from ..repetition import Repetition
         if repetition is not None and not isinstance(repetition, Repetition):
             raise MasqueError(f'{repetition} is not a valid Repetition object!')
@@ -76,6 +76,6 @@ class RepeatableImpl(Repeatable, metaclass=ABCMeta):
     '''
     ---- Non-abstract methods
     '''
-    def set_repetition(self, repetition: 'Repetition' | None) -> Self:
+    def set_repetition(self, repetition: 'Repetition | None') -> Self:
         self.repetition = repetition
         return self