added contents for MyInterface.sol

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

interface ICounter {

    function count() external view returns (uint256);

    function addToCount() external;

}

contract MyInterface is ICounter {

    uint256 counter = 0;

    function count() external view override returns (uint256) {

        return counter;

    }

    function addToCount() external override {

        counter++;

    }

}

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