ast, we have two kinds of "is this token present" funcitons:
has_star(&self) -> bool and
is_mutable(&self) -> bool.
Should we switch to the
has_mut variant? (presumable with adding
mut_token() accessors as well). It seems like "has token" fits better with pure-syntax style of API than "has property"
I think the most elegant and general approach is to only have an accessor returning the token and calling is_some() on its result when a boolean is desired