= |@math| $last |@math| $op $value * =
    |@math| $op $value $last
= |@math| $last |@math| $op * $value =
    |@math| $op $last $value

= || set new pen color? |pen color| r $g $b |@math| $r =
    |pen color| $r $g $b

= || set new pen color? |pen color| $r g $b |@math| $g =
    |pen color| $r $g $b

= || set new pen color? |pen color|$r $g  b |@math| $b =
    |pen color| $r $g $b

= || set new pen color =

= || next color |pen color| $r $g $b =
    |@math| random 50 255 |@math| random 50 255 |@math| random 100 255
    || set new pen color |pen color| r g b

= || jump |backtrack| $row $col =
    |matrix position| $row $col
    |@math| multiply $col 2 |@math| multiply $row 2
    || jump pen x || jump pen y 
    || next color
= || jump |generate| =

= || jump pen x |pen position| $oldx $y |@math| $x =
    |pen position| $x $y

= || jump pen y |pen position| $x $oldy |@math| $y =
    |pen position| $x $y

= || mark cell at |@math| $index =
    |@array| set cells $index seen

= || mark cell at? |location| $row $col =
    |@math| multiply $row 128
    |@math| add $col *
    
= || find neighbors |location| $row $col =
    || get free cell downwards  |col| downwards $col  |@math| add $row  1
    || get free cell rightwards |row| rightwards $row |@math| add $col  1
    || get free cell upwards    |col| upwards $col    |@math| add $row -1
    || get free cell leftwards  |row| leftwards $row  |@math| add $col -1

= || get free cell $dir |col| $dir $col |@math| -1  =
= || get free cell $dir |col| $dir $col |@math| 128 =
= || get free cell $dir |row| $dir $row |@math| -1  =
= || get free cell $dir |row| $dir $row |@math| 128 =

= || get free cell $dir |col| $dir $col |@math| $row =
    |@math| multiply $row 128
    |@math| add $col *
    || is $dir cell free |location| $row $col

= || get free cell $dir |row| $dir $row |@math| $col =
    |@math| multiply $row 128
    |@math| add $col *
    || is $dir cell free |location| $row $col

= || is downwards cell free |@array| cells $index |location| $row $col =
    |downwards cell| $row $col

= || is rightwards cell free |@array| cells $index |location| $row $col =
    |rightwards cell| $row $col

= || is upwards cell free |@array| cells $index |location| $row $col =
    |upwards cell| $row $col

= || is leftwards cell free |@array| cells $index |location| $row $col =
    |leftwards cell| $row $col

= || is $dir cell free |@array| cells $index $value |location| $row $col =

= || is $dir cell free? |@math| $index =
    |@array| get cells $index


= || go in direction |@math| 1 |upwards cell| $row $col =
    |matrix position| $row $col
    || mark cell at |location| $row $col
    || move up 
    || move up
    || clear navigation state

= || go in direction |@math| 2 |rightwards cell| $row $col =
    |matrix position| $row $col
    || mark cell at |location| $row $col
    || move right
    || move right
    || clear navigation state


= || go in direction |@math| 3 |downwards cell| $row $col =
    |matrix position| $row $col
    || mark cell at |location| $row $col
    || move down
    || move down
    || clear navigation state


= || go in direction |@math| 4 |leftwards cell| $row $col =
    |matrix position| $row $col
    || mark cell at |location| $row $col
    || move left 
    || move left
    || clear navigation state
    

= || go in direction? |@math| 1 |sweep|=
    |@math| 2
= || go in direction? |@math| 2 |sweep|=
    |@math| 3
= || go in direction? |@math| 3 |sweep|=
    |@math| 4
= || go in direction? |@math| 4 |sweep|=
    |@math| 1

= || go in direction |@math| $n =
    || clear navigation state || jump

= || clear navigation state |upwards cell| $r $c =
    || push location to backtrack stack
    || clear navigation state

= || clear navigation state |rightwards cell| $r $c =
    || push location to backtrack stack
    || clear navigation state

= || clear navigation state |downwards cell| $r $c =
    || push location to backtrack stack 
    || clear navigation state

= || clear navigation state |leftwards cell| $r $c =
    || push location to backtrack stack 
    || clear navigation state

= || clear navigation state? |sweep| =

= || clear navigation state? |location| $row $col =

= || clear navigation state =

= || push location to backtrack stack |location| $row $col =
    |backtrack| $row $col

= || push location to backtrack stack =

= || pick a random direction |matrix position| $row $col =
    |@math| random 1 5
    || find neighbors |location| $row $col
    || go in direction |location| $row $col |sweep| |sweep| |sweep|

= || update |generate|? =
    || pick a random direction

== 
    |@array| create cells 16384
    |matrix position| 64 64 |screen resolution| 256 256
    |pen position| 128 128
    || pen brush pencil
    || pen down
    || pen color 255 64 128
    |generate|