virOver.sol

     contract A {
         function foo()  virtual public pure returns (string memory) {
             return "Foo from A";
         }
    

         function boo()  public pure returns (string memory) {
             return "Boo from A";
         }

     }
    

     contract B is A {
         function foo()  override public pure returns (string memory) {
             return "I override the Contract A's foo function";
         }
    

         function boo2()  public pure returns (string memory) {
             return "Boo from B";
         }
        
     }