error: redundant closure
   --> src/token/formats.rs:224:22
    |
224 |             .map_err(|err| ser::Error::custom(err))?;
    |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace the closure with the function itself: `ser::Error::custom`
    |
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#redundant_closure

error: redundant closure
   --> src/token/formats.rs:221:22
    |
221 |             .map_err(|err| ser::Error::custom(err))?;
    |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace the closure with the function itself: `ser::Error::custom`
    |
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#redundant_closure

error: redundant closure
   --> src/token/formats.rs:160:22
    |
160 |             .map_err(|err| ser::Error::custom(err))?;
    |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace the closure with the function itself: `ser::Error::custom`
    |
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#redundant_closure

error: redundant closure
   --> src/token/formats.rs:157:22
    |
157 |             .map_err(|err| ser::Error::custom(err))?;
    |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace the closure with the function itself: `ser::Error::custom`
    |
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#redundant_closure
    = note: `-D clippy::redundant-closure` implied by `-D warnings`
    = help: to override `-D warnings` add `#[allow(clippy::redundant_closure)]`