> For the complete documentation index, see [llms.txt](https://andrecronje.gitbook.io/yearn-finance/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://andrecronje.gitbook.io/yearn-finance/developers/misc-resources/smart-contract-api/apr.md).

# APR

## initializeFactory

{% tabs %}
{% tab title="Smart Contract" %}

```javascript
initializeFactory((template: address));
```

{% endtab %}

{% tab title="Web3" %}

```javascript
factoryContract.methods.initializeFactory(template).send();
```

{% endtab %}
{% endtabs %}

| Parameter |                           Description |
| --------- | ------------------------------------: |
| template  | Ethereum address of exchange template |

## createExchange

{% tabs %}
{% tab title="Smart Contract" %}

```javascript
createExchange(token: address): address
```

{% endtab %}

{% tab title="Web3" %}

```javascript
factoryContract.methods.initializeFactory(token).send();
```

{% endtab %}
{% endtabs %}

| Parameter | Type    |                        Description |
| --------- | ------- | ---------------------------------: |
| token     | address | Ethereum address of an ERC20 token |

| Returns |                                        |
| ------- | -------------------------------------: |
| address | Ethereum address of a Uniswap exchange |

## getExchange

{% tabs %}
{% tab title="Smart Contract" %}

```javascript
@constant
getExchange(token: address): address
```

{% endtab %}

{% tab title="Web3" %}

```javascript
factoryContract.methods.getExchange(token).call();
```

{% endtab %}
{% endtabs %}

| Parameter | Type    |                        Description |
| --------- | ------- | ---------------------------------: |
| token     | address | Ethereum address of an ERC20 token |

| Returns |                                        |
| ------- | -------------------------------------: |
| address | Ethereum address of a Uniswap exchange |

## getToken

{% tabs %}
{% tab title="Smart Contract" %}

```javascript
@constant
getToken(exchange: address): address
```

{% endtab %}

{% tab title="Web3" %}

```javascript
factoryContract.methods.getToken(exchange).call();
```

{% endtab %}
{% endtabs %}

| Parameter | Type    |                            Description |
| --------- | ------- | -------------------------------------: |
| exchange  | address | Ethereum address of a Uniswap exchange |

| Returns |                                    |
| ------- | ---------------------------------: |
| address | Ethereum address of an ERC20 token |

## getTokenWithId

{% tabs %}
{% tab title="Smart Contract" %}

```javascript
@constant
getTokenWithId(token_id: uint256): address
```

{% endtab %}

{% tab title="Web3" %}

```javascript
factoryContract.methods.getToken(exchange).call();
```

{% endtab %}
{% endtabs %}

| Parameter | Type    |                   Description |
| --------- | ------- | ----------------------------: |
| token\_id | uint256 | Uniswap ID for an ERC20 token |

| Returns |                                    |
| ------- | ---------------------------------: |
| address | Ethereum address of an ERC20 token |