Truffle Fehler „Redeclaring an already implemented function as abstract“

Checken ob Basis abstract contract das reduzierte Interface implementiert das in Kind Contract ebenfalls implementiert ist…

contract IA {
    function myAbstractFunc() public;
}

contract IAandB is IA {
    function anotherAbstractFunc() public;
}

contract A is IA { // -> IA is important here!!!
    function myAbstractFunc() public {
        //implemented here
    }
}

contract B is A, IAandB {
    function anotherAbstractFunc() public {
        //implemented here
    }
}