$ cargo run
   Compiling structs v0.1.0 (file:///projects/structs)
error[E0106]: missing lifetime specifier
 --> src/main.rs:2:15
  |
2 |     username: &str,
  |               ^ expected lifetime parameter

error[E0106]: missing lifetime specifier
 --> src/main.rs:3:12
  |
3 |     email: &str,
  |            ^ expected lifetime parameter

error: aborting due to 2 previous errors

For more information about this error, try `rustc --explain E0106`.
error: could not compile `structs`.

To learn more, run the command again with --verbose.
