Accepts the current layer.
This is a shortcut for up.layer.current.accept().
See up.Layer#accept() for more documentation.
The acceptance value that will be passed to { onAccepted } callbacks.
If there isn't an acceptance value, omit this argument.
If you need to pass options without an acceptance value, pass null:
up.layer.accept(null, { animation: 'move-to-bottom' })