def _writeMzmlChecksum(xmlWriter, outputFile):
    """ #TODO: docstring

    :param xmlWriter: #TODO: docstring
    :param outputFile: #TODO: docstring
    """
    sha = hashlib.sha1(outputFile.getvalue())
    sha.update('<fileChecksum>')

    xmlChecksumElement = ETREE.Element('fileChecksum')
    xmlChecksumElement.text = sha.hexdigest()

    xmlWriter.write(xmlChecksumElement, pretty_print=True)