Function try_value_from 

fn try_value_from<'a, T>(
    layer: &str,
) -> impl Parser<Input<'a>, T, ErrMode<ParseStack<'a>>>
where
    T: FromStr,
    T::Err: Error + Send + Sync + 'static,

A parser helper, which returns a FromStr-style parser for types that don’t implement their own parser.

Parses until the end of the current line. The line ending itself is not consumed. Wraps the returned parser in a named layer.

Errors

Returns an error if the next token cannot be parsed into T. The error message of T::from_str is preserved as external error.