Improve *.py code quality

Also fixes some latent, rather unimportant bugs

auth.py

-import hmac, hashlib
+import hmac
+import hashlib
 import ssl
 from datetime import datetime
 
@@ -16,8 +17,9 @@ class User:
         self.permanent = permanent
 
     def summarize(self):
-        return "{}:{}:{}:{}:{}".format(self.username, ",".join(self.groups),
-            str(self.timestamp.timestamp()), self.obsolete, self.permanent)
+        return ":".join((
+            self.username, ",".join(self.groups),
+            str(self.timestamp.timestamp()), self.obsolete, self.permanent))
 
     @staticmethod
     def from_summary(summary):
@@ -45,7 +47,8 @@ class UserManager:
         for backend in self.backends:
             if backend.authenticate(username, password):
                 groups = sorted(list(set(backend.groups(username, password))))
-                return User(username, groups, obsolete=backend.obsolete,
+                return User(
+                    username, groups, obsolete=backend.obsolete,
                     permanent=permanent)
         return None
 
@@ -77,8 +80,8 @@ class SecurityManager:
         if user is None:
             return False
         session_duration = datetime.now() - user.timestamp
-        macs_equal = hmac.compare_digest(maccer.hexdigest().encode("utf-8"),
-            hash)
+        macs_equal = hmac.compare_digest(
+            maccer.hexdigest().encode("utf-8"), hash)
         time_short = int(session_duration.total_seconds()) < self.max_duration
         return macs_equal and (time_short or user.permanent)
 
@@ -104,12 +107,11 @@ class StaticUserManager:
             yield from self.group_map[username]
 
     def all_groups(self):
-        yield from list(set(group for group in groups.values()))
+        yield from list(set(group for group in self.group_map.values()))
 
 
 try:
     import ldap3
-    from ldap3.utils.dn import parse_dn
 
     class LdapManager:
         def __init__(self, host, user_dn, group_dn, port=636, use_ssl=True,
@@ -121,8 +123,8 @@ try:
 
         def authenticate(self, username, password):
             try:
-                connection = ldap3.Connection(self.server,
-                    self.user_dn.format(username), password)
+                connection = ldap3.Connection(
+                    self.server, self.user_dn.format(username), password)
                 return connection.bind()
             except ldap3.core.exceptions.LDAPSocketOpenError:
                 return False
@@ -144,16 +146,15 @@ try:
             for group in group_reader.search():
                 yield group.cn.value
 
-
     class ADManager:
         def __init__(self, host, domain, user_dn, group_dn,
                      port=636, use_ssl=True, ca_cert=None, obsolete=False):
             tls_config = ldap3.Tls(validate=ssl.CERT_REQUIRED)
             if ca_cert is not None:
-                tls_config = ldap3.Tls(validate=ssl.CERT_REQUIRED,
-                    ca_certs_file=ca_cert)
-            self.server = ldap3.Server(host, port=port, use_ssl=use_ssl,
-                tls=tls_config)
+                tls_config = ldap3.Tls(
+                    validate=ssl.CERT_REQUIRED, ca_certs_file=ca_cert)
+            self.server = ldap3.Server(
+                host, port=port, use_ssl=use_ssl, tls=tls_config)
             self.domain = domain
             self.user_dn = user_dn
             self.group_dn = group_dn
@@ -176,11 +177,13 @@ try:
             connection.bind()
             obj_def = ldap3.ObjectDef("user", connection)
             name_filter = "cn:={}".format(username)
-            user_reader = ldap3.Reader(connection, obj_def, self.user_dn,
-                name_filter)
+            user_reader = ldap3.Reader(
+                connection, obj_def, self.user_dn, name_filter)
             group_def = ldap3.ObjectDef("group", connection)
+
             def _yield_recursive_groups(group_dn):
-                group_reader = ldap3.Reader(connection, group_def, group_dn, None)
+                group_reader = ldap3.Reader(
+                    connection, group_def, group_dn, None)
                 for entry in group_reader.search():
                     yield entry.name.value
                     for child in entry.memberOf:
@@ -189,20 +192,22 @@ try:
                 for group_dn in result.memberOf:
                     yield from _yield_recursive_groups(group_dn)
 
-
         def all_groups(self):
             connection = self.prepare_connection()
             connection.bind()
             obj_def = ldap3.ObjectDef("group", connection)
             group_reader = ldap3.Reader(connection, obj_def, self.group_dn)
-            for result in reader.search():
+            for result in group_reader.search():
                 yield result.name.value
+
 except ModuleNotFoundError:
     pass
 
 
 try:
-    import grp, pwd, pam
+    import grp
+    import pwd
+    import pam
 
     class PAMManager:
         def __init__(self, obsolete=False):
@@ -224,4 +229,3 @@ try:
                 yield group.gr_name
 except ModuleNotFoundError:
     pass
-