Fix typo in sets.md regarding immutable items

website/content/03_sets_tuples_dicts/20_sets.md

@@ -4,7 +4,7 @@ date = 2020-08-29T16:54:39-07:00
 weight = 20
 +++
 
-A `set` is a mutable datatype that allows you to store **immutable** types in an **unsorted** way. Sets are mutable because you can add and remove items from them. They can contain immmutable items, like `tuple`s and other primitive types, but not `list`s, `set`s, or `dict`ionaries which are themselves mutable.
+A `set` is a mutable datatype that allows you to store **immutable** types in an **unsorted** way. Sets are mutable because you can add and remove items from them. They can contain immutable items, like `tuple`s and other primitive types, but not `list`s, `set`s, or `dict`ionaries which are themselves mutable.
 
 Unlike a list or a tuple, a set can only contain one instance of a unique item. There are no duplicates allowed.
 
@@ -229,4 +229,4 @@ Next, let's find the intersection. We'll create a new `set` with *only* the item
 
 There are other useful operations available on `set`s, such as checking if one set is a subset, a superset, differences, and more, but I don't have time to cover them all. Python also has a `frozenset` type, if you need the functionality of a `set` in an immutable package (meaning that the contents can't be changed after creation).
 
-Find out more by reading the [documentation](https://docs.python.org/3/library/stdtypes.html#set), or calling `help()` on `set`.
+Find out more by reading the [documentation](https://docs.python.org/3/library/stdtypes.html#set), or calling `help()` on `set`.