Function c2rust_refactor::ast_manip::fn_edit::flat_map_fns

pub fn flat_map_fns<T, F>(target: &mut T, callback: F) where
    T: MutVisit,
    F: FnMut(FnLike) -> SmallVec<[FnLike; 1]>, 

Similar to mut_visit_fns, but allows transforming each FnLike into a sequence of zero or more FnLikes.