diff --git a/mod_oop/3.9_10_stack_iter.py b/mod_oop/3.9_10_stack_iter.py
index e44cb01..af96b6d 100644
--- a/mod_oop/3.9_10_stack_iter.py
+++ b/mod_oop/3.9_10_stack_iter.py
@@ -54,12 +54,12 @@ class StackObj:
     @data.setter
     def data(self, value):
         self.__data = value
-    
+
     def __eq__(self, other):
         if hasattr(other, "data"):
             return self.data == other.data
         return self.data == other
-    
+
     def __ne__(self, other):
         return not self == other
 
@@ -71,7 +71,7 @@ class StackObj:
     def next(self, value):
         if isinstance(value, (self.__class__, None.__class__)):
             self.__next = value
-    
+
     @classmethod
     def wrap(cls, value):
         return value if isinstance(value, cls) else cls(value)
@@ -87,7 +87,7 @@ class Stack:
     def __init__(self, data=None):
         self.top = None
         self.load(data or [])
-    
+
     def __iter__(self):
         obj = self.top
         while obj:
@@ -106,12 +106,12 @@ class Stack:
             self.top = obj
         else:
             self.bottom.next = obj
-    
+
     def push_front(self, value):
         obj = StackObj.wrap(value)
         obj.next = self.top
         self.top = obj
-    
+
     def pop(self) -> StackObj:
         if not self.top:
             return None
@@ -123,14 +123,14 @@ class Stack:
         if b == self.top:
             self.top = None
         return b
-    
+
     def load(self, data):
         for x in data:
             self.push_back(x)
 
     def __len__(self):
         return sum(1 for _ in self)
-    
+
     def validate_index(self, idx: int):
         if not isinstance(idx, int) or not 0 <= idx < len(self):
             raise IndexError("неверный индекс")
@@ -143,18 +143,18 @@ class Stack:
 
     def __setitem__(self, idx: int, value):
         self.validate_index(idx)
-        
+
         if idx == len(self):
             self.push(value)
             return
-        
+
         prev = self.top
         for i, v in enumerate(self):
             prev = v
             if idx == i:
                 old = v
                 break
-        
+
         value = StackObj.wrap(value)
         value.next = old.next
         if idx > 0:
@@ -167,29 +167,29 @@ class Stack:
 
     def __str__(self):
         return " -> ".join(map(str, self.get_data()))
-    
+
     def __repr__(self):
         return f"{self.__class__.__name__}({self.get_data()!r})"
 
 
 def tests():
     code = (
-           b'b95j*AX9W<V{0fW3UhQWaCLKNUt(cnYbaB6VPk7gVrnQNF(N4`3UhQWaCLKNUuJS|ZgeP9bYWv'
-         + b'_Phx5)A~GT=DGCZ<b8}^KbRctdTQFT9Jv|^IG9n;hZe$>HbXzf9AU!=GA~7N?AR^Gc(6!LA(6!Nk'
-         + b'(7n-%(6u1Yx6r-Nu+fLmwa~rLxY3Uw(6rF7(7n*T(TmZAAketbw;<5I(6P~q(6!LI(Sp#v(6S)Wf'
-         + b'zg7{wa~iIuq+_ZztMouxFFEJ(6P~g(6G^o(6!LL(74dJAkexX(7n*O(7YhfztFxQ(74dO(6rFC(7'
-         + b'Mrq(Ssri3UhQ@FkK)$AR;g#3So0|WpZ>Nb97rUT_8O@AR;g#EFdD#ztFzWyU~NuhtRdqz0kfO(7n'
-         + b'*L(6Z3A(SXps(7w>MAkeqaz0k1HhtRdqz0kPOwII;A(6=DazR<DJiqN&ty3vBruprTa(Sp#m(7Mp'
-         + b'DEFjRb(7w>O(7e#T(6-RM(7r4n(7n*L(7MpR(SXr_(6!LI(Sp#u(7qtifY7kevCzKJg3z$gwb6ng'
-         + b'(7(}u(74fo(6Z35(74dD(6G?G(74dGAke+gzR<GJzR<JKz97)I(7n*G(TC8r(7n*O(T^a|zR<DJi'
-         + b'qN&ty3vBsgCNm?(Sp#m(7MpDA_@v-Z*m}SVrn31ZXk1XItm~lARu9Lb7gXLAZc@HZgX^DZewLAZ('
-         + b'?dJAX9W<V{1=hYAGxrBGA9lfY7)g(7({N(SXpk(6P|I(SXpkAkl%*g3z_ly3nv7(TC8r(SXpk(6='
-         + b'DbhS0dsy3o5I(6rFL(7VvK(7n-%AkebVzR<VOveAIhu+fRou+f6ijM0J7k08*#(6P~q(6!LI(Sp&'
-         + b'7AkezdyU?)Ffzg4`upm=(VPk7gVrn7^3UqRLItm~lARu8NJs@**TQgk>Wq4y{aC9I^Ze(S6MRIa)'
-         + b'aykkiARr)Nb8}^KbRbl6b!7@=Y;$Eg3LqdLAYpTJWpZ>NMqzAoWh@{f(7n*LAkl%)v(UBBz0kGMf'
-         + b'Y7+nfY83sve2;5yU@PTfzga0(74fo(7MpO(T>rF(6!LL(74dGAW3dyWq3t$a&K}X'
+        b"b95j*AX9W<V{0fW3UhQWaCLKNUt(cnYbaB6VPk7gVrnQNF(N4`3UhQWaCLKNUuJS|ZgeP9bYWv"
+        + b"_Phx5)A~GT=DGCZ<b8}^KbRctdTQFT9Jv|^IG9n;hZe$>HbXzf9AU!=GA~7N?AR^Gc(6!LA(6!Nk"
+        + b"(7n-%(6u1Yx6r-Nu+fLmwa~rLxY3Uw(6rF7(7n*T(TmZAAketbw;<5I(6P~q(6!LI(Sp#v(6S)Wf"
+        + b"zg7{wa~iIuq+_ZztMouxFFEJ(6P~g(6G^o(6!LL(74dJAkexX(7n*O(7YhfztFxQ(74dO(6rFC(7"
+        + b"Mrq(Ssri3UhQ@FkK)$AR;g#3So0|WpZ>Nb97rUT_8O@AR;g#EFdD#ztFzWyU~NuhtRdqz0kfO(7n"
+        + b"*L(6Z3A(SXps(7w>MAkeqaz0k1HhtRdqz0kPOwII;A(6=DazR<DJiqN&ty3vBruprTa(Sp#m(7Mp"
+        + b"DEFjRb(7w>O(7e#T(6-RM(7r4n(7n*L(7MpR(SXr_(6!LI(Sp#u(7qtifY7kevCzKJg3z$gwb6ng"
+        + b"(7(}u(74fo(6Z35(74dD(6G?G(74dGAke+gzR<GJzR<JKz97)I(7n*G(TC8r(7n*O(T^a|zR<DJi"
+        + b"qN&ty3vBsgCNm?(Sp#m(7MpDA_@v-Z*m}SVrn31ZXk1XItm~lARu9Lb7gXLAZc@HZgX^DZewLAZ("
+        + b"?dJAX9W<V{1=hYAGxrBGA9lfY7)g(7({N(SXpk(6P|I(SXpkAkl%*g3z_ly3nv7(TC8r(SXpk(6="
+        + b"DbhS0dsy3o5I(6rFL(7VvK(7n-%AkebVzR<VOveAIhu+fRou+f6ijM0J7k08*#(6P~q(6!LI(Sp&"
+        + b"7AkezdyU?)Ffzg4`upm=(VPk7gVrn7^3UqRLItm~lARu8NJs@**TQgk>Wq4y{aC9I^Ze(S6MRIa)"
+        + b"aykkiARr)Nb8}^KbRbl6b!7@=Y;$Eg3LqdLAYpTJWpZ>NMqzAoWh@{f(7n*LAkl%)v(UBBz0kGMf"
+        + b"Y7+nfY83sve2;5yU@PTfzga0(74fo(7MpO(T>rF(6!LL(74dGAW3dyWq3t$a&K}X"
     )
-    exec(__import__('base64').b85decode(code))
+    exec(__import__("base64").b85decode(code))
 
 
 if __name__ == "__main__":