Fix typo (#118)

challenges/advanced-overload-literal/question.py

@@ -1,7 +1,7 @@
 """
 TODO:
 
-foo is a function that returns an interger when second argument is 1, returns a string when second argument is 2, returns a list when second argument is 3, otherwise it returns inputs self.
+foo is a function that returns an integer when second argument is 1, returns a string when second argument is 2, returns a list when second argument is 3, otherwise it returns inputs self.
 """