clear () {
    // Set the state to TO_BE_CLEARED to mark the timer for removal in the next
    // tick by the onTick function.
    this._state = TO_BE_CLEARED

    // Reset the _idleStart value to -1 to indicate that the timer is no longer
    // active.
    this._idleStart = -1
  }
The `clear` method cancels the timer, preventing it from executing.

@returns {void}
@private