Function parse 

pub(crate) fn parse<'env: 't, 't, T>(
    _: &'env mut Environment,
    document: &'t str,
    verbose: Verbosity,
)
where
    T: Parse<'t> + Annotation + for<'a> Walk<'a, DefaultTypes> + Foldable<DefaultTypes, DefaultTypes>,
    <T as Foldable<DefaultTypes, DefaultTypes>>::Out: Annotation,