diff --git a/__crypto/simple_contract/src/cmd.rs b/__crypto/simple_contract/src/cmd.rs
index 1d669fa..8cdc3f5 100644
--- a/__crypto/simple_contract/src/cmd.rs
+++ b/__crypto/simple_contract/src/cmd.rs
@@ -1,6 +1,7 @@
 use clap::{ArgMatches, App};
 use rust_util::XResult;
 pub type CommandError = XResult<()>;
+
 pub trait Command {
     fn name(&self) -> &str;
     fn subcommand<'a>(&self) -> App<'a, 'a>;
diff --git a/__crypto/simple_contract/src/cmd_credit_create.rs b/__crypto/simple_contract/src/cmd_credit_create.rs
index ff45c93..e72df8d 100644
--- a/__crypto/simple_contract/src/cmd_credit_create.rs
+++ b/__crypto/simple_contract/src/cmd_credit_create.rs
@@ -1,10 +1,10 @@
 use std::fs;
 use clap::{App, Arg, ArgMatches, SubCommand};
-use rust_util::information;
-use crate::{cmd::{Command, CommandError}, engine_credit::CreditContractCreateParameters};
-use crate::engine::ContractEngine;
-use crate::tx::{Transaction, TransactionBody};
+use crate::cmd::{Command, CommandError};
 use crate::util::JsonKeyPair;
+use crate::tx::{Transaction, TransactionBody};
+use crate::engine::ContractEngine;
+use crate::engine_plugin_credit::CreditContractCreateParameters;
 
 pub struct CommandImpl;
 impl Command for CommandImpl {
diff --git a/__crypto/simple_contract/src/cmd_credit_issue.rs b/__crypto/simple_contract/src/cmd_credit_issue.rs
index 6260062..eff0fb0 100644
--- a/__crypto/simple_contract/src/cmd_credit_issue.rs
+++ b/__crypto/simple_contract/src/cmd_credit_issue.rs
@@ -1,10 +1,10 @@
 use std::fs;
 use clap::{App, Arg, ArgMatches, SubCommand};
-use rust_util::information;
-use crate::{cmd::{Command, CommandError}, engine_credit::CreditContractIssueParameters};
-use crate::engine::ContractEngine;
-use crate::tx::{Transaction, TransactionBody};
+use crate::cmd::{Command, CommandError};
 use crate::util::JsonKeyPair;
+use crate::tx::{Transaction, TransactionBody};
+use crate::engine::ContractEngine;
+use crate::engine_plugin_credit::CreditContractIssueParameters;
 
 pub struct CommandImpl;
 impl Command for CommandImpl {
diff --git a/__crypto/simple_contract/src/cmd_credit_query.rs b/__crypto/simple_contract/src/cmd_credit_query.rs
index 3636363..154993c 100644
--- a/__crypto/simple_contract/src/cmd_credit_query.rs
+++ b/__crypto/simple_contract/src/cmd_credit_query.rs
@@ -1,10 +1,10 @@
 use std::fs;
 use clap::{App, Arg, ArgMatches, SubCommand};
-use rust_util::information;
-use crate::{cmd::{Command, CommandError}, engine_credit::CreditContractQueryParameters};
-use crate::engine::ContractEngine;
-use crate::tx::{Transaction, TransactionBody};
+use crate::cmd::{Command, CommandError};
 use crate::util::JsonKeyPair;
+use crate::tx::{Transaction, TransactionBody};
+use crate::engine::ContractEngine;
+use crate::engine_plugin_credit::CreditContractQueryParameters;
 
 pub struct CommandImpl;
 impl Command for CommandImpl {
diff --git a/__crypto/simple_contract/src/cmd_credit_queryall.rs b/__crypto/simple_contract/src/cmd_credit_queryall.rs
index be7c6dd..c5ea074 100644
--- a/__crypto/simple_contract/src/cmd_credit_queryall.rs
+++ b/__crypto/simple_contract/src/cmd_credit_queryall.rs
@@ -1,10 +1,10 @@
 use std::fs;
 use clap::{App, Arg, ArgMatches, SubCommand};
-use rust_util::information;
-use crate::{cmd::{Command, CommandError}, engine_credit::CreditContractQueryAllParameters};
-use crate::engine::ContractEngine;
-use crate::tx::{Transaction, TransactionBody};
+use crate::cmd::{Command, CommandError};
 use crate::util::JsonKeyPair;
+use crate::tx::{Transaction, TransactionBody};
+use crate::engine::ContractEngine;
+use crate::engine_plugin_credit::CreditContractQueryAllParameters;
 
 pub struct CommandImpl;
 impl Command for CommandImpl {
diff --git a/__crypto/simple_contract/src/cmd_credit_transfer.rs b/__crypto/simple_contract/src/cmd_credit_transfer.rs
index edbf05b..1a995a7 100644
--- a/__crypto/simple_contract/src/cmd_credit_transfer.rs
+++ b/__crypto/simple_contract/src/cmd_credit_transfer.rs
@@ -1,10 +1,10 @@
 use std::fs;
 use clap::{App, Arg, ArgMatches, SubCommand};
-use rust_util::information;
-use crate::{cmd::{Command, CommandError}, engine_credit::CreditContractTransferParameters};
-use crate::engine::ContractEngine;
-use crate::tx::{Transaction, TransactionBody};
+use crate::cmd::{Command, CommandError};
 use crate::util::JsonKeyPair;
+use crate::tx::{Transaction, TransactionBody};
+use crate::engine::ContractEngine;
+use crate::engine_plugin_credit::CreditContractTransferParameters;
 
 pub struct CommandImpl;
 impl Command for CommandImpl {
diff --git a/__crypto/simple_contract/src/cmd_default.rs b/__crypto/simple_contract/src/cmd_default.rs
index a4c0c8e..6618764 100644
--- a/__crypto/simple_contract/src/cmd_default.rs
+++ b/__crypto/simple_contract/src/cmd_default.rs
@@ -1,6 +1,6 @@
 use clap::{App, Arg, ArgMatches};
-use rust_util::information;
 use crate::cmd::CommandError;
+
 pub struct CommandImpl;
 impl CommandImpl {
     pub fn process_command<'a>(app: App<'a, 'a>) -> App<'a, 'a> {
diff --git a/__crypto/simple_contract/src/cmd_genkey.rs b/__crypto/simple_contract/src/cmd_genkey.rs
index cc85267..f516dc9 100644
--- a/__crypto/simple_contract/src/cmd_genkey.rs
+++ b/__crypto/simple_contract/src/cmd_genkey.rs
@@ -1,8 +1,9 @@
 use std::fs;
 use std::fs::File;
 use clap::{App, Arg, ArgMatches, SubCommand};
-use rust_util::failure;
-use crate::{cmd::{Command, CommandError}, util::{JsonKeyPair, make_key_pair}};
+use crate::cmd::{Command, CommandError};
+use crate::util::{JsonKeyPair, make_key_pair};
+
 pub struct CommandImpl;
 impl Command for CommandImpl {
     fn name(&self) -> &str { "genkey" }
diff --git a/__crypto/simple_contract/src/credit.rs b/__crypto/simple_contract/src/credit.rs
index 2a299a6..91dcaf7 100644
--- a/__crypto/simple_contract/src/credit.rs
+++ b/__crypto/simple_contract/src/credit.rs
@@ -1,5 +1,5 @@
 use std::{collections::HashMap, fs, fs::File};
-use rust_util::{XResult, information, simple_error};
+use rust_util::XResult;
 use serde::{Serialize, Deserialize};
 use crate::tx::Transaction;
 
diff --git a/__crypto/simple_contract/src/engine.rs b/__crypto/simple_contract/src/engine.rs
index 103c468..e726e10 100644
--- a/__crypto/simple_contract/src/engine.rs
+++ b/__crypto/simple_contract/src/engine.rs
@@ -1,5 +1,6 @@
-use rust_util::{XResult, simple_error};
-use crate::{engine_credit::ContractEngineCredit, tx::Transaction};
+use rust_util::XResult;
+use crate::tx::Transaction;
+use crate::engine_plugin_credit::ContractEngineCredit;
 
 pub struct ContractEngine {
 }
diff --git a/__crypto/simple_contract/src/engine_credit.rs b/__crypto/simple_contract/src/engine_plugin_credit.rs
similarity index 95%
rename from __crypto/simple_contract/src/engine_credit.rs
rename to __crypto/simple_contract/src/engine_plugin_credit.rs
index 1c5f0b7..db9f76c 100644
--- a/__crypto/simple_contract/src/engine_credit.rs
+++ b/__crypto/simple_contract/src/engine_plugin_credit.rs
@@ -1,7 +1,7 @@
 use serde::{Serialize, Deserialize};
-use rust_util::{XResult, debugging, information, simple_error};
-use crate::{credit::CreditContract, tx::{Transaction, TransactionBody}};
-
+use rust_util::XResult;
+use crate::credit::CreditContract;
+use crate::tx::{Transaction, TransactionBody};
 
 #[derive(Debug, Serialize, Deserialize)]
 pub struct CreditContractCreateParameters {
diff --git a/__crypto/simple_contract/src/main.rs b/__crypto/simple_contract/src/main.rs
index 3eca7f2..340ef17 100644
--- a/__crypto/simple_contract/src/main.rs
+++ b/__crypto/simple_contract/src/main.rs
@@ -1,8 +1,10 @@
+#[macro_use] extern crate rust_util;
+
 pub mod util;
 pub mod tx;
 pub mod credit;
 pub mod engine;
-pub mod engine_credit;
+pub mod engine_plugin_credit;
 
 mod cmd;
 mod cmd_default;
diff --git a/__crypto/simple_contract/src/tx.rs b/__crypto/simple_contract/src/tx.rs
index 87249e8..c51be5b 100644
--- a/__crypto/simple_contract/src/tx.rs
+++ b/__crypto/simple_contract/src/tx.rs
@@ -1,7 +1,7 @@
-use rust_util::{XResult, simple_error};
+use std::str::FromStr;
+use rust_util::XResult;
 use secp256k1::{Message, PublicKey, Secp256k1, SecretKey, Signature};
 use serde::{Serialize, Deserialize};
-use std::str::FromStr;
 use crate::util::{calc_sha256, make_btc_address};
 
 #[derive(Debug, Serialize, Deserialize)]
@@ -61,4 +61,4 @@ impl Transaction {
 fn get_body_message(body: &str) -> XResult<Message> {
     let digest= calc_sha256(body.as_bytes());
     Message::from_slice(&digest).map_err(|e| e.into())
-}
\ No newline at end of file
+}