diff --git a/optree/integration/jax.py b/optree/integration/jax.py
index 01a5bccc..aa70c1dd 100644
--- a/optree/integration/jax.py
+++ b/optree/integration/jax.py
@@ -160,7 +160,7 @@ def tree_ravel(
         A pair ``(array, unravel_func)`` where the first element is a 1D array representing the
         flattened and concatenated leaf values, with ``dtype`` determined by promoting the
         ``dtype``\s of leaf values, and the second element is a callable for unflattening a 1D array
-        of the same length back to a pytree of of the same structure as the input ``tree``. If the
+        of the same length back to a pytree of the same structure as the input ``tree``. If the
         input pytree is empty (i.e. has no leaves) then as a convention a 1D empty array of the
         default dtype is returned in the first component of the output.
     """
diff --git a/optree/integration/numpy.py b/optree/integration/numpy.py
index fcdc3ef9..50099eee 100644
--- a/optree/integration/numpy.py
+++ b/optree/integration/numpy.py
@@ -89,7 +89,7 @@ def tree_ravel(
         A pair ``(array, unravel_func)`` where the first element is a 1D array representing the
         flattened and concatenated leaf values, with ``dtype`` determined by promoting the
         ``dtype``\s of leaf values, and the second element is a callable for unflattening a 1D array
-        of the same length back to a pytree of of the same structure as the input ``tree``. If the
+        of the same length back to a pytree of the same structure as the input ``tree``. If the
         input pytree is empty (i.e. has no leaves) then as a convention a 1D empty array of the
         default dtype is returned in the first component of the output.
     """
diff --git a/optree/integration/torch.py b/optree/integration/torch.py
index 9ff9f899..023d8e0a 100644
--- a/optree/integration/torch.py
+++ b/optree/integration/torch.py
@@ -86,7 +86,7 @@ def tree_ravel(
         A pair ``(tensor, unravel_func)`` where the first element is a 1D tensor representing the
         flattened and concatenated leaf values, with ``dtype`` determined by promoting the
         ``dtype``\s of leaf values, and the second element is a callable for unflattening a 1D tensor
-        of the same length back to a pytree of of the same structure as the input ``tree``. If the
+        of the same length back to a pytree of the same structure as the input ``tree``. If the
         input pytree is empty (i.e. has no leaves) then as a convention a 1D empty tensor of the
         default dtype is returned in the first component of the output.
     """
diff --git a/optree/utils.py b/optree/utils.py
index f6d4a8f9..10e8ad80 100644
--- a/optree/utils.py
+++ b/optree/utils.py
@@ -43,14 +43,12 @@ def total_order_sorted(
         if key is None:
 
             def key_fn(x: T) -> tuple[str, Any]:
-                # pylint: disable-next=consider-using-f-string
                 return (f'{x.__class__.__module__}.{x.__class__.__qualname__}', x)
 
         else:
 
             def key_fn(x: T) -> tuple[str, Any]:
                 y = key(x)
-                # pylint: disable-next=consider-using-f-string
                 return (f'{y.__class__.__module__}.{y.__class__.__qualname__}', y)
 
         try: