-- see here: http://write-up.semantic-db.org/28-simple-network-in-sw-format.html

O |a1> => |a2>
O |a2> => |a3>
O |a3> => |a4>
O |a4> => |a5>
O |a5> => |a6>
O |a6> => |a7>
O |a7> => |a8>
O |a8> => |a9>
O |a9> => |a10>
O |a10> => |a1> + |b1>

O |b1> => |b2>
O |b2> => |b3>
O |b3> => |b4>
O |b4> => |b5>
O |b5> => |b6>
O |b6> => |b7>
O |b7> => |b1>