def METHOD_NAME(self):
    logging.info('Updating CheBI ontology...')
    # https://www.gnu.org/software/wget/manual/html_node/Time_002dStamping-Usage.html
    # cmd = "wget -N ftp://ftp.ebi.ac.uk/pub/databases/chebi/ontology/chebi.obo"
    cmd = "wget -N ftp://ftp.ebi.ac.uk/pub/databases/chebi/archive/rel138/ontology/chebi.obo"
    subprocess.check_call(cmd, shell=True)
    self.filename = "chebi.obo"