Fieldset example

Hey I’d like to ask how to create a filedset in a model and how to create fields into the fieldset?
here’s my code

async function createFieldSet() {
  const ModularModelBlock = await client.itemTypes.create({
    name: 'BasicModularModel',
    apiKey: 'basic_modular_model',
  });

  const fieldset = await client.fieldset.create(ModularModelBlock.id, {
    title: 'test fieldset',
    hint: '',
    position: 1,
    collapsible: true,
    startCollapsed: false
  });
  console.log(fieldset)
}

createFieldSet()

In my code, I create a model “BasicModularModel” and create a filedset "test fieldset"in it.

and the console log shows

PS C:\work\migration> node .\test.js
{
  id: '406823',
  title: 'test fieldset',
  hint: null,
  collapsible: true,
  startCollapsed: false,
  position: 1,
  itemType: '1548164'
}

but when I check on UI, no filed has been added into the model.

Did I do something wrong?

The second question is can someone provide an example about how to create field inside the field set?
Thanks!!