  We compare two models for $\infty$-operads: the complete Segal operads of
Barwick and the complete dendroidal Segal spaces of Cisinski and Moerdijk.
Combining this with comparison results already in the literature, this implies
that all known models for $\infty$-operads are equivalent - for instance, it
follows that the homotopy theory of Lurie's $\infty$-operads is equivalent to
that of dendroidal sets and that of simplicial operads.
