Try to create a DSL for a finite state machine.

Inspired by Chris vanBuskirk version on this site and the Ruby article at

http://www-128.ibm.com/developerworks/java/library/j-cb03137/index.html

/**
* GOAL: Write a quick-and-dirty DSL in Groovy that emulates Bruce Tate's
* example "acts_as_statemachine" Ruby code at
* http://www-128.ibm.com/developerworks/java/library/j-cb03137/index.html,
* within 20 minutes or less (i.e. steer clear of MOP-magic engineering ;).
*
* For more context, see the Apr'07 "Symbols" thread on the groovy-user mailing
* list.
*/