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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def convert_ensembl_to_entrez(self, ensembl):
 """Convert Ensembl Id to Entrez Gene Id"""

        if 'ENST' in ensembl:
            pass
        else:
            raise (IndexError)
        # Submit resquest to NCBI eutils/Gene database
        server = "http://eutils.ncbi.nlm.nih.gov/entrez/eutils/esearch.fcgi?" + self.options + "&db=gene&term={0}".format(
            ensembl)
        r = requests.get(server, headers={"Content-Type": "text/xml"})
        if not r.ok:
            r.raise_for_status()
            sys.exit()
        # Process Request
        response = r.text
        info = xmltodict.parse(response)
        try:
            geneId = info['eSearchResult']['IdList']['Id']
        except TypeError:
            raise (TypeError)
        return geneId