remove redundant redeclaration

src/lib.rs

@@ -195,10 +195,8 @@ impl<'a> MessageHeaderRef<'a> {
     /// but with the size already parsed out.
     pub fn deserialize(buf: &'a [u8]) -> Result<Self, Error> {
         let (sender, buf) = deserialize_str(buf)?;
-        let sender = sender;
 
         let (group, buf) = deserialize_str(buf)?;
-        let group = group;
 
         let (id, buf) = deserialize_u32(buf)?;