code: func (tf tFiles) searchMinUkey(icmp *iComparer, umin []byte) int {
  	return sort.Search(len(tf), func(i int) bool {
  		return icmp.ucmp.Compare(tf[i].imin.ukey(), umin) > 0
  	})
  }
docs: // Searches smallest index of tables whose its smallest
  // key is after the given key.