Simple solidity example, from https://solidity.readthedocs.io/en/v0.5.11/introduction-to-smart-contracts.html

SimpleStorage.sol

pragma solidity >=0.4.0 <0.7.0;

// See https://solidity.readthedocs.io/en/v0.5.11/introduction-to-smart-contracts.html
contract SimpleStorage {
    uint storedData;

    function set(uint x) public {
        storedData = x;
    }

    function get() public view returns (uint) {
        return storedData;
    }
}

// On Ropsten @ 0x0e289dddd43d844ea0ea750679f9418d2505c897