error[E0277]: the trait bound `HashSet<u32>: Encode` is not satisfied
 --> src/main.rs:6:10
  |
6 | #[derive(Encode, Decode)]
  |          ^^^^^^ the trait `Encode` is not implemented for `HashSet<u32>`
  |
  = note: this error originates in the derive macro `Encode` (in Nightly builds, run with -Z macro-backtrace for more info)

error[E0277]: the trait bound `HashSet<u32>: Decode` is not satisfied
 --> src/main.rs:6:18
  |
6 | #[derive(Encode, Decode)]
  |                  ^^^^^^ the trait `Decode` is not implemented for `HashSet<u32>`
  |
  = note: this error originates in the derive macro `Decode` (in Nightly builds, run with -Z macro-backtrace for more info)

For more information about this error, try `rustc --explain E0277`.