You'll want to run `brew install boost@1.55`
$ brew search boost
==> Formulae
boost boost-build
boost-python boost-python@1.59
boost@1.57 boost@1.60
boost-bcp boost-mpi
boost-python3 boost@1.55 boost@1.59
==> Casks
boostnote focus-booster
iboostup nosqlbooster-for-mongodb
turbo-boost-switcher