diff --git a/demo_code.py b/demo_code.py
index 1e336515f..cacd38c76 100644
--- a/demo_code.py
+++ b/demo_code.py
@@ -10,6 +10,7 @@
 
 AWS_SECRET_KEY = "d6s$f9g!j8mg7hw?n&2"
 
+
 class BaseNumberGenerator:
     """Declare a method -- `get_number`."""
 
@@ -17,7 +18,7 @@ def __init__(self):
         self.limits = (1, 10)
 
     def get_number(self, min_max):
-        raise NotImplemented
+        raise NotImplementedError
 
     def smethod():
         """static method-to-be"""
@@ -35,7 +36,7 @@ class RandomNumberGenerator:
 
     def limits(self):
         return self.limits
-    
+
     def _test(self):
         return self.limits
 
@@ -47,6 +48,7 @@ def get_number(self, min_max=[1, 10]):
 
 class ImaginaryNumber:
     """Class to represent an imaginary number."""
+
     def __init__(self):
         self.real = 0
         self.imaginary = 1
@@ -131,11 +133,13 @@ def chained_comparison():
     c = 3
     return a < b and b < c
 
+
 def wrong_callable():
     number = ImaginaryNumber()
-    if hasattr(number, '__call__'):
+    if hasattr(number, "__call__"):
         return number()
 
+
 if __name__ == "__main__":
     args = ["--disable", "all"]
     for i in range(len(args)):