Compiler warning in src/main.rs

[spencerwilson]

Generic Issue

• Ensure this issue is not a bug report or feature request

Description
The following appears using rustc 1.58.1:

% cargo check
warning: derive helper attribute is used before it is introduced
  --> src/main.rs:9:3
   |
9  | #[structopt(
   |   ^^^^^^^^^
...
13 | #[derive(StructOpt)]
   |          --------- the attribute is introduced here
   |
   = note: `#[warn(legacy_derive_helpers)]` on by default
   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
   = note: for more information, see issue #79202 <https://github.com/rust-lang/rust/issues/79202>

warning: `electionguard_verify` (bin "verify") generated 1 warning
    Finished dev [unoptimized + debuginfo] target(s) in 0.05s

Possible Solution

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