diff --git a/src/graphemes.rs b/src/graphemes.rs
index e818e59..c9d749f 100644
--- a/src/graphemes.rs
+++ b/src/graphemes.rs
@@ -1,5 +1,6 @@
 use unicode_segmentation::UnicodeSegmentation;
 
+/// Trait extension example
 pub trait Trim {
   fn trim_count(&self, count: usize) -> String;
 }
diff --git a/src/mutate_in_closure.rs b/src/mutate_in_closure.rs
index fc1a0f4..70f4e46 100644
--- a/src/mutate_in_closure.rs
+++ b/src/mutate_in_closure.rs
@@ -1,24 +1,18 @@
-use std::cell::RefCell;
-
-/// Use ``RefCell`` to mutate a variable in a closure
-/// # Panics
-///
-pub fn mutate_in_closure() {
-  let my_string = RefCell::new("hello".to_string());
-  let mutate = |new_val| {
-    *my_string.borrow_mut() = new_val;
-  };
-  // mutate in closure
-  mutate("hej".to_string());
-  assert_eq!(*my_string.borrow(), "hej");
-
-  *my_string.borrow_mut() = "bonjour".to_string();
-  assert_eq!(*my_string.borrow(), "bonjour");
-}
-
+#[cfg(test)]
 mod tests {
+  use std::cell::RefCell;
+  /// Use ``RefCell`` to mutate a variable in a closure
   #[test]
   fn test_mutate_in_closure() {
-    super::mutate_in_closure();
+    let my_string = RefCell::new("hello".to_string());
+    let mutate = |new_val| {
+      *my_string.borrow_mut() = new_val;
+    };
+    // mutate in closure
+    mutate("hej".to_string());
+    assert_eq!(*my_string.borrow(), "hej");
+
+    *my_string.borrow_mut() = "bonjour".to_string();
+    assert_eq!(*my_string.borrow(), "bonjour");
   }
 }
diff --git a/src/vec_any.rs b/src/vec_any.rs
index 20a5e21..4b4c939 100644
--- a/src/vec_any.rs
+++ b/src/vec_any.rs
@@ -1,6 +1,6 @@
 use core::any::Any;
 
-trait AsAny {
+pub trait AsAny {
   fn as_any(&self) -> &dyn Any;
 }
 impl<T: Any + Animal> AsAny for T {
@@ -13,8 +13,8 @@ pub trait Animal {
   fn talk(&self);
 }
 
-struct Cat {}
-struct Dog {
+pub struct Cat {}
+pub struct Dog {
   pub name: String,
 }
 
@@ -29,30 +29,27 @@ impl Animal for Dog {
   }
 }
 
-trait AnyAnimal: Animal + AsAny {}
+pub trait AnyAnimal: Animal + AsAny {}
 impl<T: Animal + AsAny> AnyAnimal for T {}
-type BoxedAnimal = Box<dyn AnyAnimal>;
+pub type BoxedAnimal = Box<dyn AnyAnimal>;
 
-/// Demonstrates creating a vector of common Animal trait objects,
-/// then downcasting to a concrete Dog type instance to be able to access its fields.
-/// # Panics
-///
-pub fn downcast_concrete_type_instance_from_trait_object() {
-  let c = Cat {};
-  let d = Dog { name: "Fido".to_string() };
+#[cfg(test)]
+mod tests {
+  use super::*;
 
-  let the_zoo = [Box::new(c) as BoxedAnimal, Box::new(d) as BoxedAnimal];
+  /// Demonstrates creating a vector of common Animal trait objects,
+  /// then downcasting to a concrete Dog type instance to be able to access its fields.
+  #[test]
+  fn test_downcast_concrete_type_instance_from_trait_object() {
+    let c = Cat {};
+    let d = Dog { name: "Fido".to_string() };
 
-  the_zoo.iter().for_each(|a| a.talk());
+    let the_zoo = [Box::new(c) as BoxedAnimal, Box::new(d) as BoxedAnimal];
 
-  let x = &the_zoo[1];
-  let dog = x.as_any().downcast_ref::<Dog>().unwrap();
-  assert!(dog.name == "Fido");
-}
+    the_zoo.iter().for_each(|a| a.talk());
 
-mod tests {
-  #[test]
-  fn test_cats_and_dogs() {
-    super::downcast_concrete_type_instance_from_trait_object();
+    let x = &the_zoo[1];
+    let dog = x.as_any().downcast_ref::<Dog>().unwrap();
+    assert!(dog.name == "Fido");
   }
 }