doc+remove of unnecessary code

src/caoscrawler/sync_node.py

@@ -38,6 +38,11 @@ logger = logging.getLogger(__name__)
 
 
 class TempID(int):
+    """A special kind of int for negative temporary IDs.
+
+    This allows to identify TempIDs in the presence of String IDs.
+    A string ID might look like a negative integer.
+    """
     pass
 
 
@@ -129,8 +134,6 @@ class SyncNode:
         for p in self.parents:
             ent.add_parent(p)
         for p in self.properties:
-            if p is None:
-                continue
             entval: Any = ent.get_property(p)
             if entval is None:
                 ent.add_property(id=p.id, name=p.name, value=p.value)