compareOpIds(id1, id2) {
    const regex = /^([0-9]+)@(.*)$/
    const match1 = regex.exec(id1), match2 = regex.exec(id2)
    const counter1 = parseInt(match1[1], 10), counter2 = parseInt(match2[1], 10)
    return (counter1 < counter2) || (counter1 === counter2 && match1[2] < match2[2])
  }
Compares two operation IDs in the form `counter@actor`. Returns true if `id1` has a lower counter
than `id2`, or if the counter values are the same and `id1` has an actorId that sorts
lexicographically before the actorId of `id2`.