@startuml
hide empty members
hide circle
skinparam classAttributeIconSize 0
class _x1_ as "<x1>"
class _y1_ as "<y1>"
_x1_ -down-> _y1_
class _x2_ as "<x2>"
class _y2_ as "<y2>"
_x2_ -up--> _y2_
class _y3_ as "<y3>"
_x2_ -right---------> _y3_
class _x3_ as "<x3>"
_x3_ -down---> _y3_
class _x4_ as "<x4>"
_x4_ -right-------> _y2_
class _y4_ as "<y4>"
_x4_ -up----> _y4_
class _x5_ as "<x5>"
class _y5_ as "<y5>"
_x5_ -down-----> _y5_
class _x6_ as "<x6>"
class _y6_ as "<y6>"
_x6_ -up------> _y6_
class _x7_ as "<x7>"
class _y7_ as "<y7>"
_x7_ -down-------> _y7_
@enduml
