forward s North (e, n) = (e, n+s)
forward s South (e, n) = (e, n-s)
forward s West (e, n) = (e-s, n)
forward s East (e, n) = (e+s, n)
forward s North (e, n) = (e, n+s)
forward s South (e, n) = (e, n-s)
forward s West (e, n) = (e-s, n)
forward s East (e, n) = (e+s, n)