What is this React pattern called?

<Popper id={id} open={open} anchorEl={anchorEl} transition>
  {({ TransitionProps }) => ( // <---- This calling function which lets you pass the data to components provided by user
    <Fade {...TransitionProps}>
      <div className={classes.paper}>The content of the Popper.</div>
    </Fade>
  )}
</Popper>

<Popper id={id} open={open} anchorEl={anchorEl} transition>
  {({ TransitionProps }) => ( // <---- This calling function which lets you pass the data to components provided by user
    <Fade {...TransitionProps}>
      <div className={classes.paper}>The content of the Popper.</div>
    </Fade>
  )}
</Popper>