a value that indicates that no agent was found when using one-of, max-one-of, etc.
a command that creates a specified number of new turtles (or turtles of a specific breed) and runs any bracketed commands (if there are any) once for each turtle (or turtles of that specific breed)
a built-in turtle variable that reports the size of the turtle
a command that takes a variable and a value as input and creates a new local (limitedly-available) variable and sets its value to the inputted value
a reporter that takes two Boolean (true/false) inputs and reports true if both inputs report true and reports false if either or both inputs report false
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 empty
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