zinating
diff --git a/‎data_structures/queue/double_ended_queue.py‎
Lines changed: 18 additions & 54 deletions b/‎data_structures/queue/double_ended_queue.py‎
Lines changed: 18 additions & 54 deletions
@@ -1,42 +1,32 @@
 """
 Implementation of double ended queue.
 """
+from __future__ import annotations
+
 from dataclasses import dataclass
 from typing import Any, Iterable
 
 
 class Deque:
     """
     Deque data structure.
-
     Operations
     ----------
     append(val: Any) -> None
-
     appendleft(val: Any) -> None
-
     extend(iter: Iterable) -> None
-
     extendleft(iter: Iterable) -> None
-
     pop() -> Any
-
     popleft() -> Any
-
-
     Observers
     ---------
     is_empty() -> bool
-
-
     Attributes
     ----------
     _front: _Node
         front of the deque a.k.a. the first element
-
     _back: _Node
         back of the element a.k.a. the last element
-
     _len: int
         the number of nodes
     """
@@ -51,13 +41,12 @@ class _Node:
         """
 
         val: Any = None
-        next: "Deque._Node" = None
-        prev: "Deque._Node" = None
+        next: Deque._Node | None = None
+        prev: Deque._Node | None = None
 
     class _Iterator:
         """
         Helper class for iteration. Will be used to implement iteration.
-
         Attributes
         ----------
         _cur: _Node
@@ -66,10 +55,10 @@ class _Iterator:
 
         __slots__ = ["_cur"]
 
-        def __init__(self, cur: "Deque._Node") -> None:
+        def __init__(self, cur: Deque._Node | None) -> None:
             self._cur = cur
 
-        def __iter__(self) -> "Deque._Iterator":
+        def __iter__(self) -> Deque._Iterator:
             """
             >>> our_deque = Deque([1, 2, 3])
             >>> iterator = iter(our_deque)
@@ -95,9 +84,10 @@ def __next__(self) -> Any:
 
             return val
 
-    def __init__(self, iterable: Iterable = None) -> None:
-        self._front = self._back = None
-        self._len = 0
+    def __init__(self, iterable: Iterable[Any] | None = None) -> None:
+        self._front: Any = None
+        self._back: Any = None
+        self._len: int = 0
 
         if iterable is not None:
             # append every value to the deque
@@ -108,7 +98,6 @@ def append(self, val: Any) -> None:
         """
         Adds val to the end of the deque.
         Time complexity: O(1)
-
         >>> our_deque_1 = Deque([1, 2, 3])
         >>> our_deque_1.append(4)
         >>> our_deque_1
@@ -117,7 +106,6 @@ def append(self, val: Any) -> None:
         >>> our_deque_2.append('c')
         >>> our_deque_2
         ['a', 'b', 'c']
-
         >>> from collections import deque
         >>> deque_collections_1 = deque([1, 2, 3])
         >>> deque_collections_1.append(4)
@@ -127,7 +115,6 @@ def append(self, val: Any) -> None:
         >>> deque_collections_2.append('c')
         >>> deque_collections_2
         deque(['a', 'b', 'c'])
-
         >>> list(our_deque_1) == list(deque_collections_1)
         True
         >>> list(our_deque_2) == list(deque_collections_2)
@@ -153,7 +140,6 @@ def appendleft(self, val: Any) -> None:
         """
         Adds val to the beginning of the deque.
         Time complexity: O(1)
-
         >>> our_deque_1 = Deque([2, 3])
         >>> our_deque_1.appendleft(1)
         >>> our_deque_1
@@ -162,7 +148,6 @@ def appendleft(self, val: Any) -> None:
         >>> our_deque_2.appendleft('a')
         >>> our_deque_2
         ['a', 'b', 'c']
-
         >>> from collections import deque
         >>> deque_collections_1 = deque([2, 3])
         >>> deque_collections_1.appendleft(1)
@@ -172,7 +157,6 @@ def appendleft(self, val: Any) -> None:
         >>> deque_collections_2.appendleft('a')
         >>> deque_collections_2
         deque(['a', 'b', 'c'])
-
         >>> list(our_deque_1) == list(deque_collections_1)
         True
         >>> list(our_deque_2) == list(deque_collections_2)
@@ -194,11 +178,10 @@ def appendleft(self, val: Any) -> None:
             # make sure there were no errors
             assert not self.is_empty(), "Error on appending value."
 
-    def extend(self, iter: Iterable) -> None:
+    def extend(self, iter: Iterable[Any]) -> None:
         """
         Appends every value of iter to the end of the deque.
         Time complexity: O(n)
-
         >>> our_deque_1 = Deque([1, 2, 3])
         >>> our_deque_1.extend([4, 5])
         >>> our_deque_1
@@ -207,7 +190,6 @@ def extend(self, iter: Iterable) -> None:
         >>> our_deque_2.extend('cd')
         >>> our_deque_2
         ['a', 'b', 'c', 'd']
-
         >>> from collections import deque
         >>> deque_collections_1 = deque([1, 2, 3])
         >>> deque_collections_1.extend([4, 5])
@@ -217,7 +199,6 @@ def extend(self, iter: Iterable) -> None:
         >>> deque_collections_2.extend('cd')
         >>> deque_collections_2
         deque(['a', 'b', 'c', 'd'])
-
         >>> list(our_deque_1) == list(deque_collections_1)
         True
         >>> list(our_deque_2) == list(deque_collections_2)
@@ -226,11 +207,10 @@ def extend(self, iter: Iterable) -> None:
         for val in iter:
             self.append(val)
 
-    def extendleft(self, iter: Iterable) -> None:
+    def extendleft(self, iter: Iterable[Any]) -> None:
         """
         Appends every value of iter to the beginning of the deque.
         Time complexity: O(n)
-
         >>> our_deque_1 = Deque([1, 2, 3])
         >>> our_deque_1.extendleft([0, -1])
         >>> our_deque_1
@@ -239,7 +219,6 @@ def extendleft(self, iter: Iterable) -> None:
         >>> our_deque_2.extendleft('ba')
         >>> our_deque_2
         ['a', 'b', 'c', 'd']
-
         >>> from collections import deque
         >>> deque_collections_1 = deque([1, 2, 3])
         >>> deque_collections_1.extendleft([0, -1])
@@ -249,7 +228,6 @@ def extendleft(self, iter: Iterable) -> None:
         >>> deque_collections_2.extendleft('ba')
         >>> deque_collections_2
         deque(['a', 'b', 'c', 'd'])
-
         >>> list(our_deque_1) == list(deque_collections_1)
         True
         >>> list(our_deque_2) == list(deque_collections_2)
@@ -262,24 +240,20 @@ def pop(self) -> Any:
         """
         Removes the last element of the deque and returns it.
         Time complexity: O(1)
-
         @returns topop.val: the value of the node to pop.
-
         >>> our_deque = Deque([1, 2, 3, 15182])
         >>> our_popped = our_deque.pop()
         >>> our_popped
         15182
         >>> our_deque
         [1, 2, 3]
-
         >>> from collections import deque
         >>> deque_collections = deque([1, 2, 3, 15182])
         >>> collections_popped = deque_collections.pop()
         >>> collections_popped
         15182
         >>> deque_collections
         deque([1, 2, 3])
-
         >>> list(our_deque) == list(deque_collections)
         True
         >>> our_popped == collections_popped
@@ -302,24 +276,20 @@ def popleft(self) -> Any:
         """
         Removes the first element of the deque and returns it.
         Time complexity: O(1)
-
         @returns topop.val: the value of the node to pop.
-
         >>> our_deque = Deque([15182, 1, 2, 3])
         >>> our_popped = our_deque.popleft()
         >>> our_popped
         15182
         >>> our_deque
         [1, 2, 3]
-
         >>> from collections import deque
         >>> deque_collections = deque([15182, 1, 2, 3])
         >>> collections_popped = deque_collections.popleft()
         >>> collections_popped
         15182
         >>> deque_collections
         deque([1, 2, 3])
-
         >>> list(our_deque) == list(deque_collections)
         True
         >>> our_popped == collections_popped
@@ -340,14 +310,12 @@ def is_empty(self) -> bool:
         """
         Checks if the deque is empty.
         Time complexity: O(1)
-
         >>> our_deque = Deque([1, 2, 3])
         >>> our_deque.is_empty()
         False
         >>> our_empty_deque = Deque()
         >>> our_empty_deque.is_empty()
         True
-
         >>> from collections import deque
         >>> empty_deque_collections = deque()
         >>> list(our_empty_deque) == list(empty_deque_collections)
@@ -359,14 +327,12 @@ def __len__(self) -> int:
         """
         Implements len() function. Returns the length of the deque.
         Time complexity: O(1)
-
         >>> our_deque = Deque([1, 2, 3])
         >>> len(our_deque)
         3
         >>> our_empty_deque = Deque()
         >>> len(our_empty_deque)
         0
-
         >>> from collections import deque
         >>> deque_collections = deque([1, 2, 3])
         >>> len(deque_collections)
@@ -379,19 +345,17 @@ def __len__(self) -> int:
         """
         return self._len
 
-    def __eq__(self, other: "Deque") -> bool:
+    def __eq__(self, other: object) -> bool:
         """
         Implements "==" operator. Returns if *self* is equal to *other*.
         Time complexity: O(n)
-
         >>> our_deque_1 = Deque([1, 2, 3])
         >>> our_deque_2 = Deque([1, 2, 3])
         >>> our_deque_1 == our_deque_2
         True
         >>> our_deque_3 = Deque([1, 2])
         >>> our_deque_1 == our_deque_3
         False
-
         >>> from collections import deque
         >>> deque_collections_1 = deque([1, 2, 3])
         >>> deque_collections_2 = deque([1, 2, 3])
@@ -400,12 +364,15 @@ def __eq__(self, other: "Deque") -> bool:
         >>> deque_collections_3 = deque([1, 2])
         >>> deque_collections_1 == deque_collections_3
         False
-
         >>> (our_deque_1 == our_deque_2) == (deque_collections_1 == deque_collections_2)
         True
         >>> (our_deque_1 == our_deque_3) == (deque_collections_1 == deque_collections_3)
         True
         """
+
+        if not isinstance(other, Deque):
+            return NotImplemented
+
         me = self._front
         oth = other._front
 
@@ -422,18 +389,16 @@ def __eq__(self, other: "Deque") -> bool:
 
         return True
 
-    def __iter__(self) -> "_Iterator":
+    def __iter__(self) -> Deque._Iterator:
         """
         Implements iteration.
         Time complexity: O(1)
-
         >>> our_deque = Deque([1, 2, 3])
         >>> for v in our_deque:
         ...     print(v)
         1
         2
         3
-
         >>> from collections import deque
         >>> deque_collections = deque([1, 2, 3])
         >>> for v in deque_collections:
@@ -449,7 +414,6 @@ def __repr__(self) -> str:
         Implements representation of the deque.
         Represents it as a list, with its values between '[' and ']'.
         Time complexity: O(n)
-
         >>> our_deque = Deque([1, 2, 3])
         >>> our_deque
         [1, 2, 3]