startshape tree rule tree .5 { shape {} treeleft {} } rule tree .5 { shape {} treeright {} } rule treeleft 1 { shape {} treeleft {s .95 y 2 r -3} } rule treeright 1 { shape {} treeright {b .04 s .95 y 2 r 3} } rule treeright .125 { branch{s .8} } rule treeleft .125 { branch{s .8} } rule branch { CIRCLE {s 1.3} tree {r 45 x -1.414 y 1.414} tree {r -45 x 1.414 y 1.414} } rule shape { SQUARE{} }