insertConnectionStacks = function (button) {
  const workspace = button.getTargetWorkspace();
  Blockly.Xml.domToWorkspace(
    Blockly.utils.xml.textToDom(
      '<xml xmlns="https://developers.google.com/blockly/xml">\n' +
        '  <block type="test_connections_stack_next">\n' +
        '    <next>\n' +
        '      <block type="test_connections_stack_blue">\n' +
        '        <next>\n' +
        '          <block type="test_connections_stack_yellow">\n' +
        '            <next>\n' +
        '              <block type="test_connections_stack_yellow">\n' +
        '                <next>\n' +
        '                  <block type="test_connections_stack_red">\n' +
        '                    <next>\n' +
        '                      <block type="test_connections_stack_prev"/>\n' +
        '                    </next>\n' +
        '                  </block>\n' +
        '                </next>\n' +
        '              </block>\n' +
        '            </next>\n' +
        '          </block>\n' +
        '        </next>\n' +
        '      </block>\n' +
        '    </next>\n' +
        '  </block>\n' +
        '</xml>',
    ),
    workspace,
  );
}
Handles "insert" button in the connection stack test category. This will
insert a group of test blocks connected in a stack.
@param {!Blockly.FlyoutButton} button The flyout button.