Function lemma_disjoint_choice_left 

pub broadcast proof fn lemma_disjoint_choice_left<S1: SpecParser, S2: SpecParser, S3: SpecParser>(
    choice: Choice<S1, S2>,
    other: S3,
)

requires

disjoint_domains(choice.0, other),

disjoint_domains(choice.1, other),

ensures

#[trigger] disjoint_domains(choice, other),

A Choice parser is disjoint from another parser if both branches are.