About actor's play function

I load 4 animation egg files and want to play them one by one. So I wrote:

actor.play("1")
actor.play("2")
actor.play("3")
actor.play("4")

But , it just play the 4th animation. So how to play it one by one?

Check this snippet from the walking panda demo:

#Create the four lerp intervals needed to walk back and forth
pandaPosInterval1= pandaActor.posInterval(13,Point3(0,-10,0), startPos=Point3(0,10,0))
pandaPosInterval2= pandaActor.posInterval(13,Point3(0,10,0), startPos=Point3(0,-10,0))
pandaHprInterval1= pandaActor.hprInterval(3,Point3(180,0,0), startHpr=Point3(0,0,0))
pandaHprInterval2= pandaActor.hprInterval(3,Point3(0,0,0), startHpr=Point3(180,0,0))

#Create and play the sequence that coordinates the intervals
pandaPace = Sequence(pandaPosInterval1, pandaHprInterval1,
  pandaPosInterval2, pandaHprInterval2, name = "pandaPace")
pandaPace.loop()

the Sequence command is what you are looking for. Adding the .loop() line will make it repeat again once it finishes, if that is what you want.