async accountForPosibleTxids() {
    return; // TODO: remove
    let onchain_txs = await this.getTxs();
    let imported_txids = await this._redis.lrange('imported_txids_for_' + this._userid, 0, -1);
    for (let tx of onchain_txs) {
      if (tx.type !== 'bitcoind_tx') continue;
      let already_imported = false;
      for (let imported_txid of imported_txids) {
        if (tx.txid === imported_txid) already_imported = true;
      }

      if (!already_imported && tx.category === 'receive') {
        // first, locking...
        let lock = new Lock(this._redis, 'importing_' + tx.txid);
        if (!(await lock.obtainLock())) {
          // someone's already importing this tx
          return;
        }

        let userBalance = await this.getCalculatedBalance();
        // userBalance += new BigNumber(tx.amount).multipliedBy(100000000).toNumber();
        // no need to add since it was accounted for in `this.getCalculatedBalance()`
        await this.saveBalance(userBalance);
        await this._redis.rpush('imported_txids_for_' + this._userid, tx.txid);
        await lock.releaseLock();
      }
    }
  }
Fetches all onchain txs for user's address, and compares them to
already imported txids (stored in database); Ones that are not imported -
get their balance added to user's balance, and its txid added to 'imported' list.

@returns {Promise<void>}