never {
accept_init:
s0_init:
    if
    :: (Fr) && (p) -> goto accept_s1
    :: !(p) -> goto s0_init
    :: !(Fr) && (p) && !(q) -> goto accept_s1
    fi;
accept_s1:
    if
    :: !(q) -> goto accept_s1
    :: (Fr) -> goto accept_s1
    fi;
}