How to play animations for children of AnimationNodeStateMachine in godot4.2?

Question

How do I use AnimationNodeStateMachinePlayback.travel to call the three animations of attack_1, attack_2, and attack_3 in the child attack_state when using AnimationTree?

I tried playing it, but it didn't work:

@onready var attack_state_machine: AnimationNodeStateMachinePlayback = $AnimationTree.get("parameters/attack_state")

# @onready var attack_state_machine: AnimationNodeStateMachinePlayback = $AnimationTree.get("parameters/playback/attack_state")

attack_state_machine.travel("attack_1")

and

@onready var animation_state_machine: AnimationNodeStateMachinePlayback = $AnimationTree.get("parameters/playback")

animation_state_machine.travel("attack_state/attack_1")