  The open book decompositions of the 3-sphere whose pages are pairs of pants
have been fully understood for some time, through the lens of contact geometry.
The purpose of this note is to exhibit a purely topological derivation of the
classification of such open books, in terms of the links that form their
bindings and the corresponding monodromies. We construct all of the links and
their pair-of-pants fiber surfaces from the simplest example, a connected sum
of two Hopf links, through performing (generalized) Stallings twists. Then, by
applying the now-classical theory of genus two Heegaard diagrams in $S^3$, we
verify that the monodromies of the links in this family are the only ones
corresponding to pair-of-pants open book decompositions of $S^3$.
