feat: use rust_util use_clap

__crypto/simple_contract/src/cmd_genkey.rs

@@ -1,7 +1,7 @@
 use std::fs;
 use std::fs::File;
 use clap::{App, Arg, ArgMatches, SubCommand};
-use crate::cmd::{Command, CommandError};
+use rust_util::util_clap::{Command, CommandError};
 use crate::util::{JsonKeyPair, make_key_pair};
 
 pub struct CommandImpl;
@@ -21,12 +21,12 @@ impl Command for CommandImpl {
         let tag = sub_arg_matches.value_of("tag");
         if let Ok(_) = File::open(output) {
             failure!("Output file exists: {}", output);
-            return Ok(());
+            return Ok(None);
         }
         let (pri_key, pub_key) = make_key_pair();
         let json_key_pair = JsonKeyPair::from(pri_key, pub_key, tag.map(|t| t.into()));
         success!("Write gen key file: {}", output);
         fs::write(output, json_key_pair.to_json()?.as_bytes())?;
-        Ok(())
+        Ok(None)
     }
 }