Function lemma_disjoint_optional 

pub broadcast proof fn lemma_disjoint_optional<P: SpecParser, A: SpecParser, B: SpecParser>(
    p: P,
    optional: Optional<A, B>,
)

requires

disjoint_domains(p, optional.0),

disjoint_domains(p, optional.1),

ensures

#[trigger] disjoint_domains(p, optional),

An Optional<A, B> parser is disjoint from another parser if both A and B are.