code: func WriteBloomBits(db ethdb.Writer, bit uint, section uint64, head common.Hash, bits []byte) {
  	if err := db.Put(bloomBitsKey(bit, section, head), bits); err != nil {
  		log.Crit("Failed to store bloom bits", "err", err)
  	}
  }
docs: // WriteBloomBits stores the compressed bloom bits vector belonging to the given
  // section and bit index.