Using a gem package called zsteg to solve door 3.

luke_03/steganography.py

@@ -0,0 +1,12 @@
+#!/usr/bin/env python3.6
+import subprocess, os
+
+def main():
+	path = os.path.dirname(os.path.realpath(__file__)) + '/bilde.png' 
+	result = subprocess.run(['zsteg', path], stdout=subprocess.PIPE)
+	decode = result.stdout.decode('utf-8')
+
+	return decode
+
+if __name__ == '__main__':
+	main()

tests/test_luke03.py

@@ -1,2 +1,11 @@
+from luke_03.steganography import main
+
 def test_answer():
-   assert False 
+   answer = 'Steganography is awesome and you Knowit!'
+   output = main()
+   print(output)
+   print(answer in output)
+   if answer in output:
+      assert True
+   else:
+      assert False