SimpleStorage.sol

// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.9.0;

contract SimpleStorage {
    // comments are created like this 
    /*
    I think 
    I can also
    comment 
    like this
    */
    uint256 favoriteNumber;

    struct People {
        uint256 favoriteNumber;
        string name;
    }

    People public person = People({favoriteNumber: 69, name: "Kuba"});

    People[] public people;
    mapping(string => uint256) public nameToFavoriteNumber;

    function store( uint256 _favoriteNumber) public {
        favoriteNumber = _favoriteNumber;
    }

    function retrieve() public view returns(uint256){
        return favoriteNumber;
    }

    function addPerson( string memory _name, uint256 _favoriteNumber) public {
        people.push(People({favoriteNumber: _favoriteNumber, name: _name}));
        nameToFavoriteNumber[_name] = _favoriteNumber;
    }
}