message: refactor(cargo-tree): simplify arg-parsing logic
diff: @@ -157,15 +157,7 @@ pub fn exec(config: &mut Config, args: &ArgMatches<'_>) -> CliResult {
  let (edge_kinds, no_proc_macro) = parse_edge_kinds(config, args)?;
  let graph_features = edge_kinds.contains(&EdgeKind::Feature);
  - let pkgs_to_prune = args.values_of("prune").map_or_else(
  - || Vec::new(),
  - |ps| {
  - let mut specs = ps.map(|p| p.to_string()).collect::<Vec<_>>();
  - specs.sort_unstable();
  - specs.dedup();
  - specs
  - },
  - );
  + let pkgs_to_prune = args._values_of("prune");
  let packages = args.packages_from_flags()?;
  let mut invert = args
  