finished MVP of ring_buffer.py, though I'm not entirely satisfied with the solution

Author: davidanagy

ring_buffer/ring_buffer.py

@@ -1,4 +1,4 @@
-from doubly_linked_list import DoublyLinkedList
+from doubly_linked_list import DoublyLinkedList, ListNode
 
 
 class RingBuffer:
@@ -8,14 +8,45 @@ def __init__(self, capacity):
         self.storage = DoublyLinkedList()
 
     def append(self, item):
-        pass
+        if self.storage.length == 0:
+            self.storage.add_to_head(item)
+            self.current = self.storage.head
+        elif self.storage.length < self.capacity:
+            self.storage.add_to_tail(item)
+        else:
+            if self.current is self.storage.head:
+                self.storage.remove_from_head()
+                self.storage.add_to_head(item)
+                if self.storage.head.next:
+                    self.current = self.storage.head.next
+                else:
+                    self.current = self.storage.head
+            elif self.current is self.storage.tail:
+                self.storage.remove_from_tail()
+                self.storage.add_to_tail(item)
+                self.current = self.storage.head
+            else:
+                current_next = self.current.next
+                current_prev = self.current.prev
+                self.storage.delete(self.current)
+                new_node = ListNode(item)
+                new_node.next = current_next
+                new_node.prev = current_prev
+                current_next.prev = new_node
+                current_prev.next = new_node
+                self.storage.length += 1
+                self.current = new_node.next
 
     def get(self):
         # Note:  This is the only [] allowed
         list_buffer_contents = []
 
         # TODO: Your code here
-
+        node = self.storage.head
+        list_buffer_contents.append(node.value)
+        while node.next:
+            node = node.next
+            list_buffer_contents.append(node.value)
         return list_buffer_contents
 
 # ----------------Stretch Goal-------------------