Add fetch-channel command

src/response.rs

@@ -2,6 +2,7 @@ use std::fmt::{Debug, Display, Formatter};
 use crate::parameter::*;
 
 pub enum Response {
+    Ok,
     Data(ParameterList),
     DataList(Vec<ParameterList>),
 }
@@ -36,6 +37,9 @@ impl TryFrom<String> for Response {
 impl Debug for Response {
     fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
            match self {
+               Response::Ok => {
+                   write!(f, "Ok")
+               }
                 Response::Data(params) => {
                     write!(f, "Data:")?;
                     write!(f, "{:?};", params)?;
@@ -48,13 +52,16 @@ impl Debug for Response {
                     }
                     Ok(())
                 }
-            }
+           }
     }
 }
 
 impl Display for Response {
     fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
         match self {
+            Response::Ok => {
+                write!(f, "Ok")
+            }
             Response::Data(params) => {
                 for param in params {
                     write!(f, "{};", param)?;