green flag key ... change parameters {p,q} and redraw screen '3' ... {3,7} '4' ... {4,5} '5' ... {5,6} '7' ... {7,3} '9' ... {9,3} 'a' ... {5,8} 'b' ... {5,4}
https://en.wikipedia.org/wiki/Uniform_tilings_in_hyperbolic_plane
