Fix typo
diff --git a/Doc/library/collections.rst b/Doc/library/collections.rst
index 54c08b8..2b6f9b1 100644
--- a/Doc/library/collections.rst
+++ b/Doc/library/collections.rst
@@ -122,7 +122,7 @@
Since some set operations create new sets, the default mixin methods need
a way to create new instances from an iterable. The class constructor is
assumed to have a signature in the form ``ClassName(iterable)``.
- That assumption is factored-out to a singleinternal classmethod called
+ That assumption is factored-out to an internal classmethod called
:meth:`_from_iterable` which calls ``cls(iterable)`` to produce a new set.
If the :class:`Set` mixin is being used in a class with a different
constructor signature, you will need to override :meth:`from_iterable`