code: def upload(self, local_fn: str, remote_fn: str = '',
               dont_overwrite: bool = False):
      
      raise NotImplementedError()
docs: Uploads given file to the task. If remote_fn is not specified, dumps it
      into task current directory with the same name.
  
      Args:
        local_fn: location of file locally
        remote_fn: location of file on task
        dont_overwrite: if True, will be no-op if target file exists