diff --git a/02-runtime-check/src/main.rs b/02-runtime-check/src/main.rs
index 70bfc3d..37e9098 100644
--- a/02-runtime-check/src/main.rs
+++ b/02-runtime-check/src/main.rs
@@ -10,7 +10,7 @@ struct CredentialManager {
 impl CredentialManager {
     pub fn new() -> CredentialManager {
         CredentialManager {
-            locked: false,
+            locked: true,
             entries: HashMap::new(),
         }
     }
diff --git a/03-builder-pattern/src/main.rs b/03-builder-pattern/src/main.rs
index e6269d9..51cff0d 100644
--- a/03-builder-pattern/src/main.rs
+++ b/03-builder-pattern/src/main.rs
@@ -41,9 +41,9 @@ impl UnlockedCredentialManager {
 }
 
 fn main() {
-    let pw = LockedCredentialManager::new();
-    let mut pw = pw.unlock("pssst");
-    pw.set("foo", "bar");
-    let val = pw.get("foo");
-    pw.lock();
+    let pw_locked = LockedCredentialManager::new();
+    let mut pw_unlocked = pw_locked.unlock("pssst");
+    pw_unlocked.set("foo", "bar");
+    let val = pw_unlocked.get("foo");
+    let pw_locked = pw_unlocked.lock();
 }
diff --git a/04-typestate/src/main.rs b/04-typestate/src/main.rs
index fd6cec9..f6c9967 100644
--- a/04-typestate/src/main.rs
+++ b/04-typestate/src/main.rs
@@ -11,7 +11,7 @@ struct CredentialManager<State = Locked> {
 }
 
 impl CredentialManager {
-    pub fn new() -> CredentialManager<Locked> {
+    pub fn new() -> CredentialManager {
         CredentialManager {
             entries: HashMap::new(),
             state: std::marker::PhantomData,
@@ -46,9 +46,9 @@ impl CredentialManager<Unlocked> {
 }
 
 fn main() {
-    let pw = CredentialManager::new();
-    let mut pw = pw.unlock("pssst");
-    pw.set("foo", "bar");
-    let val = pw.get("foo");
-    pw.lock();
+    let pw_locked = CredentialManager::new();
+    let mut pw_unlocked = pw_locked.unlock("pssst");
+    pw_unlocked.set("foo", "bar");
+    let val = pw_unlocked.get("foo");
+    let pw_locked = pw_unlocked.lock();
 }
diff --git a/05-typestate-go-structs/main.go b/05-typestate-go-structs/main.go
index 6957835..18bbcbd 100644
--- a/05-typestate-go-structs/main.go
+++ b/05-typestate-go-structs/main.go
@@ -35,11 +35,9 @@ func (m UnlockedCredentialManager) Lock() LockedCredentialManager {
 }
 
 func main() {
-	pw := NewCredentialManager()
-
-	unlocked := pw.Unlock("pssst")
-	unlocked.Set("foo", "bar")
-	_, _ = unlocked.Get("foo")
-
-	unlocked.Lock()
+	pwLocked := NewCredentialManager()
+	pwUnlocked := pwLocked.Unlock("pssst")
+	pwUnlocked.Set("foo", "bar")
+	_, _ = pwUnlocked.Get("foo")
+	pwUnlocked.Lock()
 }
diff --git a/06-typestate-go-interfaces/main.go b/06-typestate-go-interfaces/main.go
index 13b5719..06d453c 100644
--- a/06-typestate-go-interfaces/main.go
+++ b/06-typestate-go-interfaces/main.go
@@ -52,3 +52,11 @@ func (t *credentialManager) Get(key string) (string, error) {
 	}
 	panic("todo")
 }
+
+func main() {
+	pwLocked := NewCredentialManager()
+	pwUnlocked, _ := pwLocked.Unlock("pssst")
+	pwUnlocked.Set("foo", "bar")
+	_, _ = pwUnlocked.Get("foo")
+	pwUnlocked.Lock()
+}
diff --git a/07-type-mapping/main.ts b/07-type-mapping/main.ts
index b7ec098..90030b5 100644
--- a/07-type-mapping/main.ts
+++ b/07-type-mapping/main.ts
@@ -22,7 +22,7 @@ type OpArgsMapping = {
 };
 
 class WebSocketClient {
-  public op<TOp extends OpCode, TArgs extends OpArgsMapping[TOp]>(
+  public send<TOp extends OpCode, TArgs extends OpArgsMapping[TOp]>(
     op: TOp,
     args: TArgs,
   ) {
@@ -32,5 +32,5 @@ class WebSocketClient {
 
 function main_ws() {
   const client = new WebSocketClient();
-  client.op(OpCode.PING, {});
+  client.send(OpCode.PING, {});
 }
diff --git a/08-type-programming/main.ts b/08-type-programming/main.ts
index 97d718f..4ada33a 100644
--- a/08-type-programming/main.ts
+++ b/08-type-programming/main.ts
@@ -1,3 +1,9 @@
+// This recursively matches path segments and parameters in segments which
+// are surrounded by curly braces (i.e. `{foo}`) in these segments.
+// The results are joined to a superset of objects with their params
+// via the `&`.
+// In example, the path /{foo}/{bar} results in the type
+// `{ foo: string } & { bar: string }`
 type ParseUrlParamsRaw<Url> = Url extends `${infer Start}/${infer Rest}`
   ? ParseUrlParamsRaw<Start> & ParseUrlParamsRaw<Rest>
   : Url extends `{${infer Param}}`
@@ -20,4 +26,5 @@ function navigate<P extends string>(path: P, params: ParseUrlParams<P>) {
 function main() {
   navigate("/hello", {});
   navigate("/hello/{name}", { name: "foo" });
+  navigate("/book/{author}/{id}", { author: "foo", id: "bar" });
 }