Update deque.py

Author: ivanmmarkovic

deque/deque.py

@@ -1,43 +1,50 @@
+
+from typing import Any, List
+
+
 class Deque:
-    def __init__(self):
-        self._deque: list = []
 
-    def add_front(self, item):
+    def __init__(self) -> None:
+        self._deque: List[Any] = []
+
+    def is_empty(self) -> bool:
+        return len(self._deque) == 0
+
+    def size(self) -> int:
+        return len(self._deque)
+
+    def add_front(self, item: Any):
         self._deque.insert(0, item)
 
-    def add_rear(self, item):
+    def add_rear(self, item: Any):
         self._deque.append(item)
 
-    def remove_front(self):
+    def remove_front(self) -> Any:
         if self.is_empty():
-            raise Exception("Deque is empty")
+            raise Exception('Deque is empty')
         return self._deque.pop(0)
 
-    def remove_rear(self):
+    def remove_rear(self) -> Any:
         if self.is_empty():
-            raise Exception("Deque is empty")
+            raise Exception('Deque is empty')
         return self._deque.pop()
 
-    def is_empty(self) -> bool:
-        return len(self._deque) == 0
-
-    def size(self) -> int:
-        return len(self._deque)
 
 
-def is_palindrome(string: str) -> bool:
+def is_palindrome(string:str='') -> bool:
     d: Deque = Deque()
+
     for character in string:
         d.add_rear(character)
 
     palindrome: bool = True
     while d.size() > 1 and palindrome:
         if d.remove_front() != d.remove_rear():
             palindrome = False
+    
     return palindrome
 
-
-print(is_palindrome("radar"))
-print(is_palindrome("radr"))
-
-
+print(is_palindrome('radar'))
+print(is_palindrome('radr'))
+print(is_palindrome('r'))
+print(is_palindrome(''))