FunWithStorage.sol

pragma solidity 0.8.7;

contract FunWithStorage {
    uint256 public cat;
    bytes32 private constant DATA_SLOT = 0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc;

    function getData() public view returns (uint256 data) {
        bytes32 slot = DATA_SLOT;
        assembly {
            data := sload(slot)
        }
    }

    function setData(uint newData) public {
        bytes32 slot = DATA_SLOT;
        assembly {
            sstore(slot, newData)
        }
    }

    function getDataAtZero() public view returns (uint256 data) {
        assembly {
            data := sload(0x0)
        }
    }

    function setCat(uint256 number) public {
        cat = number;
    }
}