a command that makes a turtle stop existing (stop executing code, disappear from any sets of agents it was in, terminate any links to that turtle, etc.)
a Boolean (true/false) reporter that takes a set of agents as input and reports true if there are any agents in the set and reports false if the set is […]
a Boolean (true/false) reporter that takes a Boolean expression as input and reports true if the Boolean expression is false and reports false if the Boolean expression is true
