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