:::info[Note]
If you wish to suggest changes on this document, please open a PR on the [Liquidity Provider Server Repository](https://github.com/rsksmart/liquidity-provider-server.git)
:::

To configure custom networks, see [Configuration](https://github.com/rsksmart/flyover-sdk/tree/main?tab=readme-ov-file#configuration) section.

## Captcha token handling 

The `tokenResolver` asynchronously fetches a token from the state managed by a store. 

```js
const tokenResolver = function () {
  return import('./store/store').then(
    (mod) => mod.store.getState().flyover.captchaToken,
  );
};
```
:::info[Info]

A Liquidity Provider can choose to enable captcha in the service to ensure only human-generated quotes.

:::

> * The function above uses the dynamic import statement to import the module located at `./store/store`. Once the module is imported, it accesses the store object from it using mod.store. Then, it retrieves the `flyover.captchaToken` from the state using `store.getState().flyover.captchaToken`. The import statement returns a promise, and the .then block is used to specify what should happen after the import is successful. In this case, it returns the captchaToken.
> * The same principle applies to any approach taken by the developer to manage the state of its application. Flyover SDK only expects a string resulting from the promise, regardless of the origin. It’s important to mention that the type of captcha expected by the Flyover SDK is a [Invisible reCAPTCHA v2](https://developers.google.com/recaptcha/docs/invisible). The site key to use the captcha is included in the LiquidityProvider object retrieved by getLiquidityProviders() function.

## Assigning Resolver in the Flyover Instance

Add the `captchaTokenResolver: tokenResolver` in the Flyover instance. 

```js
const flyover = new Flyover({
  network: 'Mainnet',
  captchaTokenResolver: tokenResolver,
  allowInsecureConnections: true,
});
```
> This will  assign the `tokenResolver` function as the captcha token resolver for the Flyover instance. This means that when the Flyover instance needs a captcha token, it will use the logic defined in `tokenResolver` to obtain it asynchronously.

## FlyoverUtils

Flyover SDK exports an object with a collection of util functions that the client application might use during the integration with the SDK. You can see the [list of the utility functions](https://github.com/rsksmart/flyover-sdk/blob/main/docs/modules.md#flyoverutils) and also when importing the FlyoverUtils object from the SDK package every function has a JsDoc explaining its usage.