Clean up and lay groundwork for challange 32

src/bytes.rs

@@ -19,10 +19,6 @@ impl Bytes {
         String::from(std::str::from_utf8(v).unwrap())
     }
 
-    pub fn to_sub_utf8(&self, length: usize) -> String {
-        Bytes(self.0[..length].to_vec()).to_utf8()
-    }
-
     pub fn len(&self) -> usize {
         self.0.len()
     }