$ src/bitcoin-cli getblockstats '"000000000000000009078f13b271c8bd3075bf77ed1fb70b08ac0cbc92545ce2"'
{
  ...
  "txs": 14,
  ...
}
$ src/bitcoin-cli getblockstats 704983
{
  ...
  "txs": 9,
  ...
}