pragma solidity 0.8.7;

abstract contract abstractHelloWorld {
    function GetValue() virtual public view returns (uint);
    function SetValue(uint _value) virtual public;
    function AddNumber(uint _value) virtual public returns (uint) {
        return 10;
    }
}

interface pureAbstractHelloWorld {
    function GetValue() external view returns (uint);
    function SetValue(uint _value) external;
}

contract HelloWorld is abstractHelloWorld{
    uint private simpleInteger;
    
    function GetValue() public override view returns (uint) {
        return simpleInteger;
    }
    
    function SetValue(uint _value) public override {
        simpleInteger = _value;
    }
    function AddNumber(uint _value) public override returns (uint ){
        return simpleInteger = _value;
    }
}