a command that takes a reporter and a set of commands as input and runs the commands repeatedly as long as the reporter reports true; if the reporter ever reports false, it stops repeating the commands
a reporter that takes a set of agents (patches or turtles) as input and reports a set of all the turtles that are on (or standing on) the same patch(es)
a reporter that takes an angle (a number) as input and reports the tangent of that angle
a command that takes a value as input and prints that value in the Command Center
a built-in turtle variable that holds the width of the line that the turtle will draw (or erase)
a command that changes turtle’s mode to drawing lines (pen-down), removing lines (pen-erase), or neither (pen-up)
a reporter that takes a distance (a number) as input and reports the patch that is that distance ahead of the current turtle (along the turtle’s current heading)
a value that indicates that no agent was found when using one-of, max-one-of, etc.