diff --git a/core/metadb/xaal/metadb/app.py b/core/metadb/xaal/metadb/app.py
index cf835bc0d0a26c552236754b2c05b45fa2c6e23d..f8d8ae8029691b6d724e2f704007db71f0ebad7c 100644
--- a/core/metadb/xaal/metadb/app.py
+++ b/core/metadb/xaal/metadb/app.py
@@ -10,7 +10,7 @@ logger = logging.getLogger(PACKAGE_NAME)
 
 
 class MetaDB(object):
-    def __init__(self,engine):
+    def __init__(self, engine):
         self.engine = engine
         self.config()
         self.setup()
@@ -44,7 +44,7 @@ class MetaDB(object):
         self.engine.add_device(dev)
         self.engine.add_timer(self.periodic_save,60)
 
-    def get_devices(self,_key=None,_value=None):
+    def get_devices(self, _key=None, _value=None):
         devices = self.cfg['devices'] 
         result = devices.keys()
         logger.debug("Searching for %s / %s" % (_key,_value))
@@ -75,21 +75,21 @@ class MetaDB(object):
                     result.remove(dev)
         return {'key':_key,'value' : _value, 'devices' : result}
 
-    def get_device(self,addr):
+    def get_device(self, addr):
         devices = self.cfg['devices']
         try:
             return devices[str(addr)]
         except KeyError:
             return None
 
-    def get_keys_values(self,_device):
+    def get_keys_values(self, _device):
         dev = self.get_device(_device)
         if dev:
             return {'device':_device,'map' : dev.dict()}
         # logger.debug('Unknown device %s' % _device)
         return {'device':_device,'map' : {}}
 
-    def get_value(self,_device,_key):
+    def get_value(self, _device, _key):
         dev = self.get_device(_device)
         if not dev:
             logger.info('Unknown device %s' % _device)
@@ -100,13 +100,13 @@ class MetaDB(object):
             logger.info('Unknown key %s for %s' % (_key,_device))
             pass
 
-    def update_keys_values(self,_device,_map):
+    def update_keys_values(self, _device, _map):
         dev = self.get_device(_device)
         updated = {}
 
         if dev:
             # if _map is empty, remove the device
-            if _map == None:
+            if _map is None:
                 # self.cfg['devices'].pop(str(_device))
                 dev = {}
                 self.dirty = True
@@ -116,15 +116,15 @@ class MetaDB(object):
                 updated.update({k:_map[k]})
                 self.dirty = True
                 # remove item if empty
-                if _map[k] == None:
+                if _map[k] is None:
                     dev.pop(k)
                 else:
                     dev.update({k:_map[k]})
                 
-        elif _map != None:
+        elif _map is not None:
             updated = {}
             for k, v in _map.items():
-                if v != None:
+                if v is not None:
                    updated.update({k:v})
             self.cfg['devices'][str(_device)]=updated
             self.dirty = True
@@ -133,8 +133,8 @@ class MetaDB(object):
             self.cfg['devices'].pop(str(_device))
 
         if len(updated):
-            body = {'device':_device,'map':updated}
-            self.engine.send_notification(self.dev,'keys_values_changed',body)
+            body = {'device':_device, 'map':updated}
+            self.engine.send_notification(self.dev, 'keys_values_changed', body)
             logger.debug(f"Updated {_device} => {self.get_device(_device)}")
             
     def periodic_save(self):
@@ -145,7 +145,7 @@ class MetaDB(object):
             #        devices.pop(key)
             devices = {key: val for key, val in sorted(devices.items(), key = lambda ele: ele[0])}
             self.cfg['devices'] = devices
-            logger.info("Saving configuration file")
+                logger.info("Saving configuration file")
             self.cfg.write()
             self.dirty = False