优化代码

src/exchange_middle_ware.rs

@@ -1,4 +1,3 @@
-use std::env;
 use std::io::{Error, ErrorKind};
 use std::sync::Arc;
 use serde_json::json;
@@ -87,7 +86,6 @@ pub struct Order {
 //     ct_val: f64,
 // }
 
-#[allow(dead_code)]
 pub struct Exchange {
     // okx okx_access_key
     okx_access_key: String,