Convert Symbol to Entrez Gene Id

def convert_symbol_to_entrezid(self, symbol):
        """Convert Symbol to Entrez Gene Id"""
        entrezdict = {}
        server = "http://rest.genenames.org/fetch/symbol/{0}".format(symbol)
        r = requests.get(server, headers={"Content-Type": "application/json"})
        if not r.ok:
            r.raise_for_status()
            sys.exit()
        response = r.text
        info = xmltodict.parse(response)
        for data in info['response']['result']['doc']['str']:
            if data['@name'] == 'entrez_id':
                entrezdict[data['@name']] = data['#text']
            if data['@name'] == 'symbol':
                entrezdict[data['@name']] = data['#text']
        return entrezdict