edit on add existing

src/main.rs

@@ -119,12 +119,14 @@ fn add(id: &String) -> io::Result<()> {
     let passphrase = login()?;
     let mut st = Storage::from_db(passphrase)?;
     if st.contains(id) {
-        // TODO: ask to edit existing in outer function which invoked this one
-        return Err(io::Error::new(
-            io::ErrorKind::InvalidInput,
-            format!("Dublicate item id: {}. Item id's must be unique.", id)
-            // TODO: ask to edit [Y/n]
-        ))
+        let question = format!("Item [{}] exist. Do you want to edit it instead?", id);
+        match get_prompt(&question)? {
+            PROMPT::YES => {
+                edit(id)?;
+                return Ok(());
+            },
+            PROMPT::NO => return Ok(()),
+        }
     }
 
     let content = editor::open_to_edit()?;