Sequence Diagrams

Only role creation

role A:
    pass

role B:
    pass

action Init:
    a = A()
    b = B()

This will create a single sequence diagram, with two actors A#1 and B#1, with a lifeline/timeline but no messages.

Simple action

role A:

    action Process:
        pass

action Init:
    a = A()

This will create a single sequence diagram, with a single actor A#1, there will be an incoming arrow with label Process to the timeline of A, that has an activation. at the end of the activation, there will be an outgoing dashed line arrow. indicating return

Two roles, one action, and a message

role A:
    action Process:
        b.Finish()
        
role B:
    func Finish():
        pass

action Init:
    a = A()
    b = B()

This will have two actors A#1 and B#1, An incoming arrow with label Process to the timeline of A#1, that has an activation. Then, there will be an arrow with label Finish from A#1 to B#1. B#1 will have an activation, and at the end of the activation, there will be an outgoing dashed line arrow from B#1 to A#1 indicating return And finally, a return arrow from A#1 to the empty left indicating return.