import { ethers } from "ethers";
import { Token, USDC } from "../contract";
/**
 * Approve token to the contract
 * @param signer evm signer
 * @param spender address of spender
 * @param token token contract instance
 * @param amount amount to approve
 * @throws error if contract call fails
 * */
export declare function approve(signer: ethers.Signer | ethers.providers.Provider, spender: string, token: USDC | Token, amount: ethers.BigNumberish, overrides?: ethers.Overrides): Promise<void>;