@startuml
!include <material/shield_half_full>

left to right direction
skinparam defaultTextAlignment center

rectangle "<$ma_shield_half_full>\nGuard" as block #LightPink

interface " " as q1
interface " " as q2
interface " " as q3
interface " " as q4
interface " " as q5

q1 --> block: input
q2 -> block: leave
block --> q3: guarded
block -> q4: unguarded
block -u-> q5: blocked
@enduml
