To run the site with Twoslash enabled you need to use yarn start.
Code samples on the TypeScript Website should run through Twoslash which lets the compiler do more of the work.
Without twoslash a code sample looks like:
```ts
// Declare a tuple type
let x: [string, number];
// Initialize it
x = ["hello", 10]; // OK
// Initialize it incorrectly
x = [10, "hello"]; // Error
```
With twoslash:
```ts twoslash
// Declare a tuple type
let x: [string, number];
// Initialize it
x = ["hello", 10]; // OK
// Initialize it incorrectly
x = [10, "hello"]; // Error
```
This would now break the TypeScript website build because the code sample has a compiler error, this is great. Let's fix that by telling TypeScript this error is on purpose:
```ts twoslash
// @errors: 2322
// Declare a tuple type
let x: [string, number];
// Initialize it
x = ["hello", 10]; // OK
// Initialize it incorrectly
x = [10, "hello"]; // Error
```
Now it will pass. The thing from here is that the comments are kind redundant because the compiler will tell you that info, so let's trim those:
```ts twoslash
// @errors: 2322
// Declare a tuple type
let x: [string, number];
// Initialize it
x = ["hello", 10];
// Initialize it incorrectly
x = [10, "hello"];
```
A twoslash code sample can do a lot - the best documentation for twoslash lives inside the bug workbench where you can test your code sample live and read how it all works.