diff --git a/src/static-guarantees/typestate-programming.md b/src/static-guarantees/typestate-programming.md
index 9f21150..9bd70f4 100644
--- a/src/static-guarantees/typestate-programming.md
+++ b/src/static-guarantees/typestate-programming.md
@@ -6,40 +6,42 @@ The concept of [typestates] describes the encoding of information about the curr
 [Builder Pattern]: https://doc.rust-lang.org/1.0.0/style/ownership/builders.html
 
 ```rust
-#[derive(Debug)]
-struct Foo {
-    inner: u32,
-}
-
-struct FooBuilder {
-    a: u32,
-    b: u32,
-}
-
-impl FooBuilder {
-    pub fn new(starter: u32) -> Self {
-        Self {
-            a: starter,
-            b: starter,
-        }
+pub mod foo_module {
+    #[derive(Debug)]
+    pub struct Foo {
+        inner: u32,
     }
 
-    pub fn double_a(self) -> Self {
-        Self {
-            a: self.a * 2,
-            b: self.b,
-        }
+    pub struct FooBuilder {
+        a: u32,
+        b: u32,
     }
 
-    pub fn into_foo(self) -> Foo {
-        Foo {
-            inner: self.a + self.b,
+    impl FooBuilder {
+        pub fn new(starter: u32) -> Self {
+            Self {
+                a: starter,
+                b: starter,
+            }
+        }
+
+        pub fn double_a(self) -> Self {
+            Self {
+                a: self.a * 2,
+                b: self.b,
+            }
+        }
+
+        pub fn into_foo(self) -> Foo {
+            Foo {
+                inner: self.a + self.b,
+            }
         }
     }
 }
 
 fn main() {
-    let x = FooBuilder::new(10)
+    let x = foo_module::FooBuilder::new(10)
         .double_a()
         .into_foo();
 
@@ -60,4 +62,4 @@ Because Rust has a [Strong Type System], there is no easy way to magically creat
 
 [Strong Type System]: https://en.wikipedia.org/wiki/Strong_and_weak_typing
 
-This allows us to represent the states of our system as types, and to include the necessary actions for state transitions into the methods that exchange one type for another. By creating a `FooBuilder`, and exchanging it for a `Foo` object, we have walked through the steps of a basic state machine.
\ No newline at end of file
+This allows us to represent the states of our system as types, and to include the necessary actions for state transitions into the methods that exchange one type for another. By creating a `FooBuilder`, and exchanging it for a `Foo` object, we have walked through the steps of a basic state machine.