add return type hint to get_node_at

Author: miguelHx

Python/chapter02/2.3 - Delete Middle Node/miguel_2.3_soln.py

@@ -57,7 +57,7 @@ def append_to_head(self, d: int) -> None:
         self.head = new_head
         self.size += 1
 
-    def get_node_at(self, index: int):
+    def get_node_at(self, index: int) -> Node:
         if index < 0 or index >= self.size:
             raise IndexError('list index out of range')
         n = self.head