> For the complete documentation index, see [llms.txt](https://docs.fringe.fi/smart-contract-documentation/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.fringe.fi/smart-contract-documentation/openzeppelin/contracts-upgradeable/interfaces/ierc3156flashlenderupgradeable.md).

# IERC 3156 Flash Lender Upgradeable

*Interface of the ERC3156 FlashLender, as defined in <https://eips.ethereum.org/EIPS/eip-3156\\[ERC-3156>]. Available since v4.1.*

## Methods

### flashFee

```solidity
function flashFee(address token, uint256 amount) external view returns (uint256)
```

*The fee to be charged for a given loan.*

#### Parameters

| Name   | Type    | Description                |
| ------ | ------- | -------------------------- |
| token  | address | The loan currency.         |
| amount | uint256 | The amount of tokens lent. |

#### Returns

| Name | Type    | Description                                                                         |
| ---- | ------- | ----------------------------------------------------------------------------------- |
| \_0  | uint256 | The amount of `token` to be charged for the loan, on top of the returned principal. |

### flashLoan

```solidity
function flashLoan(contract IERC3156FlashBorrowerUpgradeable receiver, address token, uint256 amount, bytes data) external nonpayable returns (bool)
```

*Initiate a flash loan.*

#### Parameters

| Name     | Type                                      | Description                                                               |
| -------- | ----------------------------------------- | ------------------------------------------------------------------------- |
| receiver | contract IERC3156FlashBorrowerUpgradeable | The receiver of the tokens in the loan, and the receiver of the callback. |
| token    | address                                   | The loan currency.                                                        |
| amount   | uint256                                   | The amount of tokens lent.                                                |
| data     | bytes                                     | Arbitrary data structure, intended to contain user-defined parameters.    |

#### Returns

| Name | Type | Description |
| ---- | ---- | ----------- |
| \_0  | bool | undefined   |

### maxFlashLoan

```solidity
function maxFlashLoan(address token) external view returns (uint256)
```

*The amount of currency available to be lended.*

#### Parameters

| Name  | Type    | Description        |
| ----- | ------- | ------------------ |
| token | address | The loan currency. |

#### Returns

| Name | Type    | Description                                 |
| ---- | ------- | ------------------------------------------- |
| \_0  | uint256 | The amount of `token` that can be borrowed. |


---

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