some cleanng

src/animals.rs

@@ -1,8 +1,3 @@
-use std::cell::Cell;
-use std::cell::Ref;
-use std::cell::RefCell;
-use std::cell::RefMut;
-
 use crate::slot::Slot;
 use std::rc::Rc;
 
@@ -44,6 +39,7 @@ impl AnimalDB {
         }
     }
 
+    #[allow(dead_code)]
     pub fn enable_debug(&mut self, yes: bool) {
         self.enable_debug = yes;
     }
@@ -84,7 +80,7 @@ impl AnimalDB {
         drop(following); // must drop this lease, or .take() will panic
         let old_animal = Rc::try_unwrap(updated_branch.take()).unwrap();
 
-        let mut new_q = NodeStruct {
+        let new_q = NodeStruct {
             kind: NodeType::Question,
             text: question,
             branch_true: Slot::new(),
@@ -98,7 +94,7 @@ impl AnimalDB {
 
         user.notify_new_animal(&new_name);
 
-        let mut new_animal = NodeStruct {
+        let new_animal = NodeStruct {
             kind: NodeType::Animal,
             text: new_name,
             branch_true: Slot::new(),

src/main.rs

@@ -94,7 +94,7 @@ macro_rules! map(
 );
 
 fn main() {
-    let mut db = animals::AnimalDB::new();
+    let db = animals::AnimalDB::new();
 
     let duck = AnswerMachine {
         answer: "duck".to_string(),

src/slot.rs

@@ -8,6 +8,7 @@ pub struct Slot<T> {
     v: RefCell<Option<Rc<T>>>,
 }
 
+#[allow(dead_code)] // some methods are unused, shut up the compiler
 impl<T> Slot<T> {
     /// Create a slot
     ///