diff --git a/exercises/ex04/ex04.py b/exercises/ex04/ex04.py
index 47339f7..00975a2 100644
--- a/exercises/ex04/ex04.py
+++ b/exercises/ex04/ex04.py
@@ -1,4 +1,4 @@
-# Exercise 1
+# Exercise 4
 # 1. Getting help with -help or -h.
 # 2. A least three arguments that are flags, meaning they don’t take an extra
 #    argument but simply putting them on the command line turns something on.
@@ -10,12 +10,12 @@
 import argparse
 
 parser = argparse.ArgumentParser()
-parser.add_argument('filename')
-parser.add_argument('-o1', '--opt1')
-parser.add_argument('-o2', '--opt2')
-parser.add_argument('-o3', '--opt3')
-parser.add_argument('-f1', '--flag1', action='store_true')
-parser.add_argument('-f2', '--flag2', action='store_true')
-parser.add_argument('-f3', '--flag3', action='store_true')
+parser.add_argument("filename")
+parser.add_argument("-o1", "--opt1")
+parser.add_argument("-o2", "--opt2")
+parser.add_argument("-o3", "--opt3")
+parser.add_argument("-f1", "--flag1", action="store_true")
+parser.add_argument("-f2", "--flag2", action="store_true")
+parser.add_argument("-f3", "--flag3", action="store_true")
 args = parser.parse_args()
 print(args)
diff --git a/exercises/ex05/ex05.py b/exercises/ex05/ex05.py
index d1423e0..57acbad 100644
--- a/exercises/ex05/ex05.py
+++ b/exercises/ex05/ex05.py
@@ -1,13 +1,15 @@
-# Exercise 2
+# Exercise 5
 # 1. cat command
 
 import argparse
 from pathlib import Path
 
 parser = argparse.ArgumentParser()
-parser.add_argument('paths', nargs="+", type=Path)
-parser.add_argument('-b', '--number-nonblank', default=False, action="store_true")
-parser.add_argument('-n', '--number', default=False, action="store_true")
+parser.add_argument("paths", nargs="+", type=Path)
+parser.add_argument(
+    "-b", "--number-nonblank", default=False, action="store_true"
+)
+parser.add_argument("-n", "--number", default=False, action="store_true")
 args = parser.parse_args()
 count = 1
 rest = 0
@@ -15,16 +17,16 @@ out = []
 
 for path in args.paths:
     if path.is_file():
-        for line in open(path, 'r').readlines():
+        for line in open(path, "r").readlines():
             blank = len(line.strip()) == 0 and args.number_nonblank
             if blank:
-                out.append({"ln": 0, "txt": ''})
+                out.append({"ln": 0, "txt": ""})
             else:
                 out.append({"ln": count, "txt": line.rstrip()})
                 count += 1
 
 for el in out:
-    line = ''
+    line = ""
     blank = len(el["txt"].strip()) == 0 and args.number_nonblank
     if args.number and not blank:
         total_width = len(str(out[-1]["ln"] - rest))
diff --git a/exercises/ex06/ex06.py b/exercises/ex06/ex06.py
index f6aacdd..df19dc3 100644
--- a/exercises/ex06/ex06.py
+++ b/exercises/ex06/ex06.py
@@ -1,4 +1,4 @@
-# Exercise 2
+# Exercise 6
 # 1. find command
 
 import sys
diff --git a/exercises/ex07/ex07.py b/exercises/ex07/ex07.py
index a220c5e..f98c903 100644
--- a/exercises/ex07/ex07.py
+++ b/exercises/ex07/ex07.py
@@ -1,4 +1,4 @@
-# Exercise 2
+# Exercise 7
 # 1. grep command
 
 import re
@@ -40,9 +40,9 @@ def grep(path, args):
 
 
 parser = argparse.ArgumentParser()
-parser.add_argument('paths', nargs="+", type=Path)
-parser.add_argument('-i', '--ignore-case', default=False, action="store_true")
-parser.add_argument('-E', '--extended-regexp', default=False, type=str)
+parser.add_argument("paths", nargs="+", type=Path)
+parser.add_argument("-i", "--ignore-case", default=False, action="store_true")
+parser.add_argument("-E", "--extended-regexp", default=False, type=str)
 
 if len(sys.argv) > 1:
     if sys.argv[1] != "-E" and sys.argv[1] != "-i":
diff --git a/exercises/ex08/ex08.py b/exercises/ex08/ex08.py
index 300c14a..5fe12a0 100644
--- a/exercises/ex08/ex08.py
+++ b/exercises/ex08/ex08.py
@@ -1,4 +1,4 @@
-# Exercise 2
+# Exercise 8
 # 1. cut command
 
 import re
@@ -31,9 +31,9 @@ def parse(fields):
 
 
 parser = argparse.ArgumentParser()
-parser.add_argument('stream', default=sys.stdin, nargs="?")
-parser.add_argument('-d', '--delimiter', default=False, type=str)
-parser.add_argument('-f', '--fields', type=str, required=True)
+parser.add_argument("stream", default=sys.stdin, nargs="?")
+parser.add_argument("-d", "--delimiter", default=False, type=str)
+parser.add_argument("-f", "--fields", type=str, required=True)
 args = parser.parse_args()
 
 for line in args.stream: