@staticmethod
def use_release_str(version):
    """
        On the Chembl FTP server, all data for a release is in a subfolder 'chembl_24_2'.

        :return: String for release directory.
        :rtype: str
        """
    version_string = '_'.join(str(version).split('.'))
    return 'chembl_{}'.format(version_string)
