Rust unpacking

main.rs

    let r2: Result<((String, (Vec<&str>, Vec<char>)), &str), ParseError> = heading.parse("**  r&wr");
    println!("{:?}", r2);
    let ((r3, (_, _)), _, _) = r2;
    println!("{:?}", r3);

src/main.rs:50:9: 50:29 error: mismatched types:
 expected `core::result::Result<((collections::string::String, (collections::vec::Vec<&str>, collections::vec::Vec<char>)), &str), parser_combinators::primitives::ParseError>`,
    found `(_, _, _)`
(expected enum `core::result::Result`,
    found tuple) [E0308]
src/main.rs:50     let ((r3, (_, _)), _, _) = r2;//.clone().map(|x| r2.ok().unwrap());
                       ^~~~~~~~~~~~~~~~~~~~