docs: def esearch(self, db, term):
          """query the esearch endpoint
          """
          esr = ESearchResult(self._qs.esearch({'db': db, 'term': term}))
          if esr.count > esr.retmax:
              logger.warning("NCBI found {esr.count} results, but we truncated the reply at {esr.retmax}"
                          " results; see https://github.com/biocommons/eutils/issues/124/".format(esr=esr))
          return esr