def upload(self, fileobj, bucket, key, extra_args=None, subscribers=None):
        """Uploads a file to S3

        :type fileobj: str or seekable file-like object
        :param fileobj: The name of a file to upload or a seekable file-like
            object to upload. It is recommended to use a filename because
            file-like objects may result in higher memory usage.

        :type bucket: str
        :param bucket: The name of the bucket to upload to

        :type key: str
        :param key: The name of the key to upload to

        :type extra_args: dict
        :param extra_args: Extra arguments that may be passed to the
            client operation

        :type subscribers: list(s3transfer.subscribers.BaseSubscriber)
        :param subscribers: The list of subscribers to be invoked in the
            order provided based on the event emit during the process of
            the transfer request.

        :rtype: s3transfer.futures.TransferFuture
        :returns: Transfer future representing the upload
        """
        if extra_args is None:
            extra_args = {}
        if subscribers is None:
            subscribers = []
        self._validate_all_known_args(extra_args, self.ALLOWED_UPLOAD_ARGS)
        call_args = CallArgs(
            fileobj=fileobj, bucket=bucket, key=key, extra_args=extra_args,
            subscribers=subscribers
        )
        extra_main_kwargs = {}
        if self._bandwidth_limiter:
            extra_main_kwargs['bandwidth_limiter'] = self._bandwidth_limiter
        return self._submit_transfer(
            call_args, UploadSubmissionTask, extra_main_kwargs)