class MyComponent {
  render() {}
}

// use a construct signature
var myComponent = new MyComponent();

// element class type => MyComponent
// element instance type => { render: () => void }

function MyFactoryFunction() {
  return {
    render: () => {
    }
  }
}

// use a call signature
var myComponent = MyFactoryFunction();

// element class type => FactoryFunction
// element instance type => { render: () => void }