Method has

src/utils/IdSet.js:199–205

* @param {number} client * @param {number} clock

(client, clock)

   * @param {number} clock
   */
  has (client, clock) {
    const dr = this.clients.get(client)
    if (dr) {
      return findIndexInIdRanges(dr.getIds(), clock) !== null
    }
    return false
  }

  /**
   * Return slices of ids that exist in this idset.