Function parse_inner 

fn parse_inner<'item, I: Iterator<Item = Result<Token<'item>, Error>>, const NESTED: bool, const VERSION: usize>(
    tokens: &mut Lexed<I>,
) -> impl Iterator<Item = Result<Item<'item>, Error>> + '_

Available on (crate features formatting or parsing) and crate feature alloc only.

Parse the provided tokens into an AST. The const generic indicates whether the resulting Item will be used directly or as part of a NestedFormatDescription.