### Calling the `remove_liquidity_one_coin` function Let's go over the solution for calling the `remove_liquidity_one_coin` function. First, we'll take a look at the interface `ITriCrypto.sol`. Inside this interface we see that we need to call the function `remove_liquidity_one_coin`. We will copy this function and paste it into the exercise. ```javascript pool.remove_liquidity_one_coin() ``` The contract that we'll be calling is the `pool` contract. The output of this function call will be the amount of tokens returned from the pool contract. The inputs for this function call are: `lp`: the amount of LP shares to burn. `i`: the index of the token that we wish to get back. `min_amount`: the minimum amount of the token that we expect to get back. `use_eth`: whether we want ETH back. `receiver`: the address that will receive the tokens. Let's prepare the inputs, we will return all the LP shares owned by this contract. ```javascript uint256 lpBal = pool.balanceOf(address(this)) ``` Once we have the LP balance we will specify it as the first input for the `remove_liquidity_one_coin` function. ```javascript lp: lpBal ``` The next input is `i`. This will be the index of the token that we wish to get back. For this exercise we want USDC back, and it's index is `0`. ```javascript i: 0 ``` The next input is the `min_amount`. This is the minimum amount of USDC that we expect to get back. We will just specify this as `1`. ```javascript min_amount: 1 ``` The next input is `use_eth`. We want USDC back, so we will specify this as `false`. ```javascript use_eth: false ``` The final input is `receiver`. The receiver of the USDC will be this contract. ```javascript receiver: address(this) ``` That completes this exercise. Let's execute this test. The name of the test is `test_remove_liquidity_one_coin`. In order to execute the test we need to match the test name in the command. Here we are using forge to run the test. ```bash forge test \ --evm-version cancun \ --fork-url $FORK_URL \ --match-test test_remove_liquidity_one_coin\\b \ --match-path test/curve-v2/exercises/CurveV2RemoveLiquidity.test.sol -vvv ``` The test passes. Inside the logs, the amount of USDC that we got back is approximately 9.99 x 10^8, which is about 999 USDC. The amount of WBTC and WETH that we got back is zero, because when calling the function `remove_liquidity_one_coin`, we specified that the token that we wanted liquidity back in is only USDC.