+ (section
+ :title [caster]
+ (p [the caster will go at the back of the robot and provide a third
+ point of contact for the robot, making it easier for it to
+ balance.])
+ (figure
+ :legend "caster"
+ (video :file "4-caster-to-deck.ogv"))
+ (p [check])
+ (enumerate
+ (item [what would happen if the robot did not have a caster?])))