docs: def trimmed(self,thresh=0.1):
          """
          m.trimmed(,thresh=0.1)  -- Return motif with low-information flanks removed.  'thresh' is in bits.
          """
          for start in range(0,self.width-1):
              if self.bits[start]>=thresh: break
          for stop  in range(self.width,1,-1):
              if self.bits[stop-1]>=thresh: break
          m = self[start,stop]
          return m