|# A turnstile, a state machine. #|

|:state: locked :action: push| :state: locked
|:state: locked :action: coin| :state: un-locked

|:state: un-locked :action: push| :state: locked
|:state: un-locked :action: coin| :state: un-locked

|| :state: locked :action: (push coin coin push)




|# A restaurant, a petri net. #|

|:customer 1: :waiter free:| :customer 1 waiting: :order taken:
|:customer 2: :waiter free:| :customer 2 waiting: :order taken:

|:customer 1 waiting: :waiter free:| :customer 1 eating: :waiter free:
|:customer 2 waiting: :waiter free:| :customer 2 eating: :waiter free:

|:order taken:| :waiter free:

|| :customer 1: :customer 2: :waiter free:




|# Taking transit, a flow chart. #|

|:ask: before 7 AM| :yes:

|:step: leave home|
    :step: check time

|:step: check time :yes:| :step: take subway
|:step: check time :no: | :step: take bus
|:step: check time|
    :ask: before 7 AM
    :step: check time

|:step: take bus   | :step: reach school
|:step: take subway| :step: reach school

||:step: leave home