code: def was_modified_since_last_sync(self):
          
          info = self.get_sync_info()
          if not info:
              return None
          if self.size != info["s"]:
              return True
          if self.mtime > info["m"]:
              return True
          return False
docs: Return True if this resource was modified since last sync.
  
          None is returned if we don't know (because of missing meta data).