# createVoucher

Creates a voucher output while processing an advance request.

## Usage

The following example creates a voucher output of a ERC-20 transfer of 1 CTSI from the application to user `0x8f7599fa6fDDF2845a3beBcDCb055C7Ba1793a1f`.

```ts twoslash
import { createApp } from "@deroll/app";
import { encodeFunctionData, erc20Abi, parseUnits } from "viem";

// create application
const app = createApp();

// log incoming advance request
app.addAdvanceHandler(async (data) => {
    const token = "0x491604c0FDF08347Dd1fa4Ee062a822A5DD06B5D"; // CTSI address // [!code focus]
    const to = "0x8f7599fa6fDDF2845a3beBcDCb055C7Ba1793a1f"; // CTSI recipient // [!code focus]
    const amount = parseUnits("1", 18); // [!code focus]

    const id = await app.createVoucher({ // [!code focus]
        destination: token, // [!code focus]
        payload: encodeFunctionData({ // [!code focus]
            abi: erc20Abi, // [!code focus]
            functionName: "transfer", // [!code focus]
            args: [to, amount], // [!code focus]
        }), // [!code focus]
    }); // [!code focus]
    return "accept";
});
```

## Returns

Type: `number`

The id of the voucher output.

## Parameters

### destination

Type: `Address`

The address of the target smart contract of the voucher.

### value

Type: `bigint | undefined`

Optional amount of native token (in wei) to send to the `destination` when the voucher is executed. Defaults to `0`.

### payload

Type: `Hex | undefined`

The ABI-encoded solidity call. Optional, so a voucher can transfer `value` to `destination` without calling any function.