Q = ^{}
P = ^ Level {
  if (Level > 0) {
    Print "Calling Q at level ", Level, EoL
    Q Level - 1
    Print "Called Q, Exiting P at level ", Level, EoL
  }
}
Q = ^ Level {
  if (Level > 0) {
    Print "Calling P at level ", Level, EoL
    P Level - 1
    Print "Called P, Exiting Q at level ", Level, EoL
  }
}

P 10