def METHOD_NAME(self, chemical_substance_id):
    """
    This takes a chembl curie id and return a chebi curie id
    """
    if chemical_substance_id[:7] == "ChEMBL:":
        chemical_substance_id = chemical_substance_id.replace("ChEMBL:", "CHEMBL")
    if chemical_substance_id.startswith('CHEMBL:CHEMBL'):
        chemical_substance_id = chemical_substance_id.replace("CHEMBL:", "")
    handler = 'chem/' + chemical_substance_id + '?fields=chebi.chebi_id'
    url = QueryMyChem.API_BASE_URL + '/' + handler
    try:
        res = requests.get(url, timeout=QueryMyChem.TIMEOUT_SEC)
    except requests.exceptions.Timeout:
        #print(url, file=sys.stderr)
        #print('Timeout in QueryMyChem for URL: ' + url, file=sys.stderr)
        return None
    if res is None:
        return None
    status_code = res.status_code
    if status_code != 200:
        #print(url, file=sys.stderr)
        #print('Status code ' + str(status_code) + ' for url: ' + url, file=sys.stderr)
        return None
    id_json = res.json()
    if 'chebi' in id_json.keys():
        return id_json['chebi']['chebi_id']
    else:
        return None