code: def save(self, **edgeArgs) :
          
  
          if not getattr(self, "_from") or not getattr(self, "_to") :
              raise AttributeError("You must specify '_from' and '_to' attributes before saving. You can also use the function 'links()'")
  
          payload = self._store.getStore()
          payload["_from"] = self._from
          payload["_to"] = self._to
          Document._save(self, payload, **edgeArgs)
docs: Works like Document's except that you must specify '_from' and '_to' vertices before.
          There's also a links() function especially for first saves.