Grammar:
S ::= a d | A d
A ::= A a | ε

Input: ad$

Parser:
        spawn(L_S, Call { label: L_S, pos: 0 }, 0)
L_S(0)
        spawn(L_S_1, Call { label: L_S, pos: 0 }, 0)
        spawn(L_S_2_0, Call { label: L_S, pos: 0 }, 0)
L_S_1(0)
        ret(Call { label: (L_S), pos: 0 }, 2)
L_S_2_0(0)
        call(Call { label: (L_A), pos: 0 }, L_S_2_1, Call { label: (L_S), pos: 0 })
L_A(0)
        spawn(L_A_1_0, Call { label: (L_A), pos: 0 }, 0)
        spawn(L_A_2, Call { label: (L_A), pos: 0 }, 0)
L_A_1_0(0)
        call(Call { label: (L_A), pos: 0 }, L_A_1_1, Call { label: (L_A), pos: 0 })
L_A(0)
        spawn(L_A_1_0, Call { label: (L_A), pos: 0 }, 0)
        spawn(L_A_2, Call { label: (L_A), pos: 0 }, 0)
L_A_2(0)
        ret(Call { label: (L_A), pos: 0 }, 0)
        spawn(L_S_2_1, Call { label: (L_S), pos: 0 }, 0)
        spawn(L_A_1_1, Call { label: (L_A), pos: 0 }, 0)
L_S_2_1(0)
L_A_1_1(0)
        ret(Call { label: (L_A), pos: 0 }, 1)
        spawn(L_S_2_1, Call { label: (L_S), pos: 0 }, 1)
        spawn(L_A_1_1, Call { label: (L_A), pos: 0 }, 1)
L_S_2_1(1)
        ret(Call { label: (L_S), pos: 0 }, 2)
L_A_1_1(1)