sp {attack*propose*turn
   (state <s> ^name attack
              ^io.input-link.radar.tank <tank>)
  (<tank> ^distance 0
          ^position { << left right >> <dir> })
   -->
   (<s> ^operator <o> + =)
   (<o> ^name turn
        ^actions <a>)
   (<a> ^rotate.direction <dir>
        ^fire.weapon missile)}
