How does HeadlessUI expose 'open' to the caller?

[AnimeAllstar]

I was taking a look at headlessUI and I found the way it exposes the internal state to the caller really cool and useful. I wasn't able to find any way to do it myself so I wanted to know how exactly they expose the internal state to the caller.

import { Menu } from '@headlessui/react'

function MyDropdown() {
  return (
    <Menu>
      {({ open }) => (
        <>
          <Menu.Button>More</Menu.Button>
          {open && (
            <div>
              {/*
                Using the `static` prop, the `Menu.Items` are always
                rendered and the `open` state is ignored.
              */}
              <Menu.Items static>
                <Menu.Item>{/* ... */}</Menu.Item>
                {/* ... */}
              </Menu.Items>
            </div>
          )}
        </>
      )}
    </Menu>
  )
}