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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _force_close(self, file_length=None):
 """Close this buffer on file_length. Finalize this upload immediately on file_length. Contents that are still in memory will not be uploaded. This is a utility method that does not modify self. Args: file_length: file length. Must match what has been uploaded. If None, it will be queried from GCS. """

    if file_length is None:
      file_length = self._get_offset_from_gcs() + 1
    self._send_data('', 0, file_length)