diff --git a/black.py b/black.py
index 087683a34f5..376c0d24299 100644
--- a/black.py
+++ b/black.py
@@ -5156,7 +5156,7 @@ def generate_ignored_nodes(leaf: Leaf) -> Iterator[LN]:
     """
     container: Optional[LN] = container_of(leaf)
     while container is not None and container.type != token.ENDMARKER:
-        if fmt_on(container):
+        if is_fmt_on(container):
             return
 
         # fix for fmt: on in children
@@ -5170,7 +5170,11 @@ def generate_ignored_nodes(leaf: Leaf) -> Iterator[LN]:
             container = container.next_sibling
 
 
-def fmt_on(container: LN) -> bool:
+def is_fmt_on(container: LN) -> bool:
+    """Determine whether formatting is switched on within a container.
+
+    Determined by whether the last `# fmt:` comment is `on` or `off`.
+    """
     is_fmt_on = False
     for comment in list_comments(container.prefix, is_endmarker=False):
         if comment.value in FMT_ON:
@@ -5181,6 +5185,8 @@ def fmt_on(container: LN) -> bool:
 
 
 def contains_fmt_on_at_column(container: LN, column: int) -> bool:
+    """Determine if children at a given column have formatting switched on.
+    """
     for child in container.children:
         if (
             isinstance(child, Node)
@@ -5188,13 +5194,14 @@ def contains_fmt_on_at_column(container: LN, column: int) -> bool:
             or isinstance(child, Leaf)
             and child.column == column
         ):
-            if fmt_on(child):
+            if is_fmt_on(child):
                 return True
 
     return False
 
 
 def first_leaf_column(node: Node) -> Optional[int]:
+    """Returns the column of the first leaf child of a node."""
     for child in node.children:
         if isinstance(child, Leaf):
             return child.column
diff --git a/docs/reference/reference_functions.rst b/docs/reference/reference_functions.rst
index 459e4980ae7..fc5cefb241b 100644
--- a/docs/reference/reference_functions.rst
+++ b/docs/reference/reference_functions.rst
@@ -135,6 +135,12 @@ Utilities
 
 .. autofunction:: black.generate_ignored_nodes
 
+.. autofunction:: black.is_fmt_on
+
+.. autofunction:: black.contains_fmt_on_at_column
+
+.. autofunction:: black.first_leaf_column
+
 .. autofunction:: black.generate_trailers_to_omit
 
 .. autofunction:: black.get_future_imports