local pi = p{ 0, 0 }
local pdx = p{ 0.25, 0 }
local pdy = p{ 0, 0.25 }
for k = 1, 20
do
local sign = 1
if k % 2 == 0 then sign = -1 end
local pn = pi + sign * k * pdx
local pn2 = pn + sign * k * pdy
draw{ line{ pi, pn }, line{ pn, pn2 } }
pi = pn2
end
