beginning_of_program
define_new_instruction turnright as
iterate 3 times
turnleft;
define_new_instruction zig_zag_d as
{if front_is_clear then
{turnright; 
move;
turnleft;
move;}
else
turnleft;}
define_new_instruction zig_zag_i as
{if front_is_clear then
{turnleft;
move;
turnright;
move;}}

beginning_of_execution



turnoff;

end_of_execution
end_of_program