rename total_fee to selected_fee, to better reflect the purpose

lib/src/commands.rs

@@ -554,16 +554,16 @@ impl Command for SendCommand {
         // If they can have different fees, you need to modify this logic.
         
         let default_fee: u64 = DEFAULT_FEE.try_into().unwrap(); 
-        let mut total_fee = default_fee;  
+        let mut selected_fee, = default_fee;  
 
             for (_, _, _, fee) in send_args.iter() {
             if *fee != default_fee{
-                total_fee = *fee;
+                selected_fee, = *fee;
                 break;  
     }
 }
         // Execute the transaction and handle the result.
-        match lightclient.do_send(tos, &total_fee) {
+        match lightclient.do_send(tos, &selected_fee,) {
             Ok(txid) => object!{ "txid" => txid }.pretty(2),
             Err(e) => object!{ "error" => e }.pretty(2),
         }