abstract contract AdminControl is Ownable, IAdminControl, ERC165 {
    using EnumerableSet for EnumerableSet.AddressSet;

    // Track registered admins
    EnumerableSet.AddressSet private _admins;

    /**
     * @dev See {IERC165-supportsInterface}.
     */
    function supportsInterface(bytes4 interfaceId) public view virtual override(ERC165, IERC165) returns (bool) {
        return interfaceId == type(IAdminControl).interfaceId
            || super.supportsInterface(interfaceId);
    }

    /**
     * @dev Only allows approved admins to call the specified function
     */
    modifier adminRequired() {
        require(owner() == msg.sender || _admins.contains(msg.sender), "AdminControl: Must be owner or admin");
        _;
    }   

    /**
     * @dev See {IAdminControl-getAdmins}.
     */
    function getAdmins() external view override returns (address[] memory admins) {
        admins = new address[](_admins.length());
        for (uint i = 0; i < _admins.length(); i++) {
            admins[i] = _admins.at(i);
        }
        return admins;
    }

    /**
     * @dev See {IAdminControl-approveAdmin}.
     */
    function approveAdmin(address admin) external override onlyOwner {
        if (!_admins.contains(admin)) {
            emit AdminApproved(admin, msg.sender);
            _admins.add(admin);
        }
    }

    /**
     * @dev See {IAdminControl-revokeAdmin}.
     */
    function revokeAdmin(address admin) external override onlyOwner {
        if (_admins.contains(admin)) {
            emit AdminRevoked(admin, msg.sender);
            _admins.remove(admin);
        }
    }

    /**
     * @dev See {IAdminControl-isAdmin}.
     */
    function isAdmin(address admin) public override view returns (bool) {
        return (owner() == admin || _admins.contains(admin));
    }

}
function revokeAdmin(address admin) external override onlyOwner {
    if (_admins.contains(admin)) {
        emit AdminRevoked(admin, msg.sender);
        _admins.remove(admin);
    }
}

/**
 * @dev See {IAdminControl-revokeAdmin}.
 */