$ENTRY Go {
    , (((1 2) (3 4 1) 5)): e.Template
    , "Payload#0" "Payload#1" "Payload#2" "Payload#3"
      "Payload#4" "Payload#5" "Payload#6": e.Payload
    = <Prout <Subst (e.Payload) e.Template>>;
};

Subst {
    (e.P) = ;
    (e.P) s.I e.X = <Item s.I e.P> <Subst (e.P) e.X>;
    (e.P) (e.X) e.Y = (<Subst (e.P) e.X>) <Subst (e.P) e.Y>;
};

Item {
    0   t.I e.X = t.I;
    s.N t.I e.X = <Item <- s.N 1> e.X>;
};