<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def convert_uniprot_to_entrez(self, uniprot):
 """Convert Uniprot Id to Entrez Id"""

        # Submit request to NCBI eutils/Gene Database
        server = "http://eutils.ncbi.nlm.nih.gov/entrez/eutils/esearch.fcgi?" + self.options + "&db=gene&term={0}".format(
            uniprot)
        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)
        geneId = info['eSearchResult']['IdList']['Id']
        # check to see if more than one result is returned
        # if you have more than more result then check which Entrez Id returns the same uniprot Id entered.
        if len(geneId) > 1:
            for x in geneId:
                c = self.convert_entrez_to_uniprot(x)
                c = c.lower()
                u = uniprot.lower()
                if c == u:
                    return x
        else:
            return geneId