diff --git a/automol/util/_util.py b/automol/util/_util.py
index 900aa2c5..b65a936c 100644
--- a/automol/util/_util.py
+++ b/automol/util/_util.py
@@ -24,8 +24,9 @@ def partner(pair: Collection, item: Any) -> Any:
 
 def flatten(lst: Collection) -> Iterator:
     """Flatten an arbitrarily nested list of lists (iterator).
-
-    Source: https://stackoverflow.com/a/2158532
+    Source: https://stackoverflow.com/a/2158532 .
+    :param lst: An arbitrarily nested list or tuple
+    :return: An iterator over the flattened list of values.
     """
     for elem in lst:
         if isinstance(elem, Iterable) and not isinstance(elem, str | bytes):
@@ -72,7 +73,7 @@ def is_odd_permutation(seq1: list, seq2: list) -> bool:
     return not is_even_permutation(seq1, seq2)
 
 
-def is_even_permutation(seq1: list, seq2: list, check: bool = True) -> bool:
+def is_even_permutation(seq1: Sequence, seq2: Sequence, check: bool = True) -> bool:
     """Determine whether a permutation of a sequence is even.
 
     :param seq1: The first sequence
@@ -189,10 +190,12 @@ def move_items_to_front(lst: Sequence, items) -> tuple:
     return tuple(lst)
 
 
-def breakby(lst: Collection, elem) -> tuple[tuple, tuple]:
+def breakby(lst: Sequence, elem) -> tuple[tuple, tuple]:
     """Break a list by element, dropping the element itself.
-
     Analogous to '<char>'.split('<string>') for strings.
+    :param lst: The list
+    :param elem: The element to break the list by, gets deleted
+    :return:The chunks between the break points of the input list.
     """
     lsts = tuple(
         tuple(g) for k, g in itertools.groupby(lst, lambda x: x == elem) if not k
@@ -200,23 +203,35 @@ def breakby(lst: Collection, elem) -> tuple[tuple, tuple]:
     return lsts
 
 
-def separate_negatives(lst: Sequence):
-    """Seperate a list of numbers into negative and nonnegative (>= 0)."""
+def separate_negatives(lst: Sequence) -> tuple[tuple, tuple]:
+    """Seperate a list of numbers into negative and nonnegative (>= 0).
+    :param lst: The list
+    :return: Value for negatives and for non-negatives.
+    """
     neg_lst = tuple(val for val in lst if val < 0)
     pos_lst = tuple(val for val in lst if val >= 0)
 
     return neg_lst, pos_lst
 
 
-def value_similar_to(val: float, lst: Collection[float], thresh: float) -> bool:
-    """Check if a value is close to some lst of values within some threshold."""
+def value_similar_to(val: float, lst: Sequence[float], thresh: float) -> bool:
+    """Check if a value is close to any one of a list of values.
+    :param val: A number.
+    :param lst: A collection of numbers to compare to.
+    :param thresh: The comparison threshold.
+    :return: 'True' if close, 'False' if not.
+    """
     return any(abs(val - vali) < thresh for vali in lst)
 
 
 def scale_iterable(
     iterable: Collection[float], scale_factor: float
 ) -> Collection[float]:
-    """Scale some type of iterable of floats by a scale factor."""
+    """Scale some type of iterable of floats by a scale factor.
+    :param iterable: A list of numbers.
+    :param scale_factor: A factor to scale by.
+    :return: The scaled list of numbers.
+    """
     if isinstance(iterable, list):
         iterable = [val * scale_factor for val in iterable]
     elif isinstance(iterable, tuple):
@@ -225,8 +240,13 @@ def scale_iterable(
     return iterable
 
 
-def remove_duplicates_with_order(lst: list):
-    """Remove all duplicates of a list while not reordering the list."""
+def remove_duplicates_with_order(lst: Sequence) -> Sequence:
+    """Remove all duplicates of a list while not reordering the list.
+    :param lst: A list.
+    :return: A list, without duplicates.
+    Note: To be deprecated
+    and replaced with calls to more_itertools.unique_justseen.
+    """
     if isinstance(lst, list):
         lst = [n for i, n in enumerate(lst) if n not in lst[:i]]
     if isinstance(lst, tuple):
diff --git a/automol/util/matrix.py b/automol/util/matrix.py
index 32aaf301..f7d754c4 100644
--- a/automol/util/matrix.py
+++ b/automol/util/matrix.py
@@ -7,9 +7,8 @@ def string(mat: Sequence[Sequence[float]], val_format="{0:>8.3f}") -> str:
     """Write a matrix to a string.
 
     :param mat: matrix to form string with
-    :type mat: tuple(tuple(float))
-    :param precision: number of integers past decimal
-    :type precision: int
+    :param val_format: A number-formatting string, such as "{:.3f}"
+    :return: Matrix as a string
     """
     mat_str = ""
     for row in mat:
diff --git a/automol/util/ring.py b/automol/util/ring.py
index a8067220..5609d513 100644
--- a/automol/util/ring.py
+++ b/automol/util/ring.py
@@ -1,19 +1,11 @@
-r"""Functions for dealing with a list of items encoding a ring
-
-                             1---2
-                            /     \
-  [1, 2, 3, 4, 5, 6]  <=>  6       3
-                            \     /
-                             5---4
-"""
+"""Functions for dealing with a list of items encoding a ring."""
 
 import itertools
-from typing import List, Tuple
 
 import more_itertools as mit
 
 
-def normalize(items: List[object]) -> List[object]:
+def normalize(items: list[object]) -> list[object]:
     """Normalize the ordering of items in a ring.
 
     :param items: The ring items
@@ -28,7 +20,7 @@ def normalize(items: List[object]) -> List[object]:
     return cycle(items, count=items.index(start_item))
 
 
-def cycle(items: List[object], count: int = 1) -> List[object]:
+def cycle(items: list[object], count: int = 1) -> list[object]:
     """Cycle ring items once.
 
     Example:    (1, 2, 3, 4) -> (2, 3, 4, 1)
@@ -42,7 +34,7 @@ def cycle(items: List[object], count: int = 1) -> List[object]:
     return tuple(itertools.islice(cycler, nitems))
 
 
-def edges(items: List[object]) -> List[object]:
+def edges(items: list[object]) -> list[object]:
     """Get the edge pairs of a ring.
 
     Example:    (1, 2, 3, 4) -> ((1, 2), (2, 3), (3, 4), (4, 1))
@@ -54,23 +46,18 @@ def edges(items: List[object]) -> List[object]:
 
 
 def distance(
-    items: List[object], item1: object, item2: object, longest: bool = False
+    items: list[object], item1: object, item2: object, longest: bool = False
 ) -> int:
-    """Find the distance between two items in a ring
+    """Find the distance between two items in a ring.
 
     By default, finds the shortest distance. Setting `longest=True` results in the
     longest distance.
 
     :param items: The ring items
-    :type items: List[object]
     :param item1: The item to start measuring distance from
-    :type item1: object
     :param item2: The item to measure distance to
-    :type item2: object
     :param longest: Return the longest distance?, defaults to False
-    :type longest: bool, optional
     :return: The number of ring items between these two
-    :rtype: int
     """
     assert (
         item1 in items and item2 in items
@@ -95,21 +82,17 @@ def distance(
 
 
 def cycle_item_to_front(
-    items: List[object], item: object, end_item: object = None
-) -> List[object]:
-    """Cycle ring items until one is in front
+    items: list[object], item: object, end_item: object = None
+) -> list[object]:
+    """Cycle ring items until one is in front.
 
     Optionally, request one adjacent item to be at the end, reversing the ring order if
     necessary.
 
     :param items: The ring items
-    :type items: List[object]
     :parm item: The item to cycle to the font
-    :type item: object
     :param end_item: optionally, ensure that this is the last item in the ring
-    :type end_item: object
     :returns: The ring items with `item` cycled to the front and `end_item` to the end
-    :rtype: List[int]
     """
     items = cycle_items_to_front(items, [item])
 
@@ -124,16 +107,13 @@ def cycle_item_to_front(
 
 
 def cycle_items_to_front(
-    items: List[object], front_items: List[object]
-) -> List[object]:
-    """Cycle ring items until a group of adjacent items is at the front of the list
+    items: list[object], front_items: list[object]
+) -> list[object]:
+    """Cycle ring items until a group of adjacent items is at the front of the list.
 
     :param items: The ring items
-    :type items: List[object]
     :parm front_items: The item to cycle to the font
-    :type front_items: List[object]
     :returns: The ring items with `item` cycled to the front and `end_item` to the end
-    :rtype: List[int]
     """
     nitems = len(items)
 
@@ -149,15 +129,12 @@ def cycle_items_to_front(
     return tuple(itertools.islice(cycler, nitems))
 
 
-def cycle_items_to_back(items: List[object], back_items: List[object]) -> List[object]:
-    """Cycle ring items until a group of adjacent items is at the end of the list
+def cycle_items_to_back(items: list[object], back_items: list[object]) -> list[object]:
+    """Cycle ring items until a group of adjacent items is at the end of the list.
 
     :param items: The ring items
-    :type items: List[object]
     :parm back_items: The item to cycle to the end
-    :type back_items: List[object]
     :returns: The ring items `back_items` cycled to the end
-    :rtype: List[int]
     """
     nitems = len(items)
 
@@ -174,16 +151,15 @@ def cycle_items_to_back(items: List[object], back_items: List[object]) -> List[o
 
 
 def cycle_to_split(
-    items: List[object], split_pair: Tuple[object, object]
-) -> List[object]:
-    """Cycle to split a pair of adjacent items, putting one on each end of the list
+    items: list[object], split_pair: tuple[object, object]
+) -> list[object]:
+    """Cycle to split a pair of adjacent items, putting one on each end of the list.
 
     :param items: The ring items
     :type items: List[object]
     :param split_pair: The pair of items to split
     :type split_pair: Tuple[object, object]
     :return: The ring items with one item in the pair at the start and one at the end
-    :rtype: List[object]
     """
     nitems = len(items)
     split_pair = set(split_pair)
@@ -211,21 +187,17 @@ def cycle_to_split(
 
 
 def cycle_to_optimal_split(
-    items: List[object],
-    split_pairs: List[Tuple[object, object]],
-    back_items: List[object],
-) -> List[object]:
+    items: list[object],
+    split_pairs: list[tuple[object, object]],
+    back_items: list[object],
+) -> list[object]:
     """Cycle to find an "optimum split" that puts a subset of items as close as possible
-    to the end of the list
+    to the end of the list.
 
     :param items: The ring items
-    :type items: List[object]
     :param split_pairs: Pairs where the cycle can be split
-    :type split_pairs: List[Tuple[object, object]]
     :param back_items: Adjacent items that should be as close to the end as possible
-    :type back_items: List[object]
     :return: The cycle with the optimal split
-    :rtype: List[object]
     """
     orig_items = items
     split_pairs = list(split_pairs)
diff --git a/docs/source/automol/heuristic.md b/docs/source/automol/heuristic.md
deleted file mode 100644
index 963d0589..00000000
--- a/docs/source/automol/heuristic.md
+++ /dev/null
@@ -1,4 +0,0 @@
-# automol.heuristic
-```{eval-rst}
-.. automodule:: automol.util.heuristic
-```
\ No newline at end of file
diff --git a/docs/source/automol/matrix.md b/docs/source/automol/matrix.md
deleted file mode 100644
index 08be1806..00000000
--- a/docs/source/automol/matrix.md
+++ /dev/null
@@ -1,5 +0,0 @@
-# automol.matrix
-some words
-```{eval-rst}
-.. automodule:: automol.util.matrix
-```
\ No newline at end of file
diff --git a/docs/source/automol/util.md b/docs/source/automol/util.md
index 56ae457c..cdbd1923 100644
--- a/docs/source/automol/util.md
+++ b/docs/source/automol/util.md
@@ -2,4 +2,18 @@
 some words
 ```{eval-rst}
 .. automodule:: automol.util
+```
+## automol.util.heuristic
+```{eval-rst}
+.. automodule:: automol.util.heuristic
+```
+## automol.util.matrix
+some words
+```{eval-rst}
+.. automodule:: automol.util.matrix
+```
+## automol.ring
+some words
+```{eval-rst}
+.. automodule:: automol.util.ring
 ```
\ No newline at end of file
diff --git a/docs/source/index.md b/docs/source/index.md
index 097e8cc0..c3c411f9 100644
--- a/docs/source/index.md
+++ b/docs/source/index.md
@@ -6,6 +6,4 @@ Welcome to my documentation website...
 :hidden:
 automol/inchi_key.md
 automol/util.md
-automol/heuristic.md
-automol/matrix.md
 ```
diff --git a/lint.sh b/lint.sh
index c908c4e9..e445b70b 100755
--- a/lint.sh
+++ b/lint.sh
@@ -7,6 +7,7 @@ FILES=(
     "automol/util/__init__.py"
     "automol/util/heuristic.py"
     "automol/util/matrix.py"
+    "automol/util/ring.py"
 )
 
 (