never {
accept_init:
s0_init:
    if
    :: !(p) -> goto s0_init
    :: (q) -> goto s0_init
    :: (p) && !(q) -> goto s1
    fi;
s1:
    if
    :: (q) -> goto s0_init
    :: (p) && !(q) -> goto s1
    :: !(p) && !(q) -> goto s2
    fi;
s2:
    if
    :: (q) -> goto s2
    :: !(p) -> goto s2
    :: (p) && !(q) -> goto s3
    fi;
s3:
    if
    :: (q) -> goto s2
    :: !(p) -> goto s2
    :: (p) && !(q) -> goto s3
    fi;
}