docs: def bestseqs(self,thresh=None):
          """
          m.bestseqs(,thresh=None)  -- Return all k-mers that match motif with a score >= thresh
          """
          if not thresh:
              if self._bestseqs:
                  return self._bestseqs
          if not thresh: thresh = 0.8 * self.maxscore
          self._bestseqs = bestseqs(self,thresh)
          return self._bestseqs