explain the purpose of each of these

nixos/modules/tests/exercise-storage.py

 #!/usr/bin/env python3
 
+#
+# Create a new file via the web interface of a Tahoe-LAFS client node and then
+# retrieve the contents of that file.  Exit with success if the retrieved
+# contents match what was uploaded originally.
+#
+
 from sys import argv
 from os import urandom
 from subprocess import check_output
@@ -23,11 +29,13 @@ def get_api_root(path):
     with open(path + u"/node.url") as f:
         return f.read().strip()
 
+
 def put(api_root, data):
     response = requests.put(api_root + u"uri", BytesIO(data))
     response.raise_for_status()
     return response.text
 
+
 def get(api_root, cap):
     response = requests.get(api_root + u"uri/" + cap, stream=True)
     response.raise_for_status()

nixos/modules/tests/get-passes.py

 #!/usr/bin/env python3
 
+#
+# Get a paid voucher and tell the Tahoe-LAFS client node to redeem it for some
+# ZKAPs from an issuer.  Exit with success when the Tahoe-LAFS client node
+# reports that the voucher has been redeemed.
+#
+
 from sys import argv
 from requests import post, get, put
 from json import dumps

nixos/modules/tests/run-client.py

 #!/usr/bin/env python3
 
+#
+# Create a PrivateStorage.io-enabled Tahoe-LAFS client node and run it as a
+# daemon.  Exit with success when we think we've started it.
+#
+
 from os import environ
 from sys import argv
 from shutil import which

nixos/modules/tests/run-introducer.py

 #!/usr/bin/env python3
 
+#
+# Create a Tahoe-LAFS introducer node and run it as a daemon.  Exit with
+# success when it is accepting introducer client connections.
+#
+
 from sys import argv
 from os import environ, makedirs, rename
 from shutil import which