diff --git a/merkly/utils.py b/merkly/utils.py
index 7d3f357..824699e 100644
--- a/merkly/utils.py
+++ b/merkly/utils.py
@@ -10,7 +10,9 @@
 class PowerOfTwoError(Exception):
     def __init__(self, number):
         self.number = number
-        super().__init__(f"Size of leafs should be a power of 2 your leafs length is: {number}")
+        super().__init__(
+            f"Size of leafs should be a power of 2 your leafs length is: {number}"
+        )
 
 
 class InvalidHashFunctionError(Exception):
diff --git a/test/utils/test_crypto.py b/test/utils/test_crypto.py
index d5f3686..4371dc2 100644
--- a/test/utils/test_crypto.py
+++ b/test/utils/test_crypto.py
@@ -3,7 +3,6 @@
 from typing import List
 
 
-
 @mark.parametrize(
     "full, half",
     [