code: def get_ncbi_taxon_num_by_label(label):
          
          req = {'db': 'taxonomy', 'retmode': 'json', 'term': label}
          req.update(EREQ)
  
          request = SESSION.get(ESEARCH, params=req)
          LOG.info('fetching: %s', request.url)
          request.raise_for_status()
          result = request.json()['esearchresult']
  
          # Occasionally eutils returns the json blob
          # {'ERROR': 'Invalid db name specified: taxonomy'}
          if 'ERROR' in result:
              request = SESSION.get(ESEARCH, params=req)
              LOG.info('fetching: %s', request.url)
              request.raise_for_status()
              result = request.json()['esearchresult']
  
          tax_num = None
          if 'count' in result and str(result['count']) == '1':
              tax_num = result['idlist'][0]
          else:
              # TODO throw errors
              LOG.warning('ESEARCH for taxon label "%s"  returns %s', label, str(result))
  
          return tax_num
docs: Here we want to look up the NCBI Taxon id using some kind of label.
          It will only return a result if there is a unique hit.
  
          :return: