AttributeError: module 'openmc.mgxs' has no attribute 'MGXSLibrary'

Hello,

I am using the latest version of OpenMC 0.15.dev but when I try to run the line

mgxs_lib.build_library()
mgxs_lib.load_from_statepoint(sp)
mgxs_hdf5 = mgxs.MGXSLibrary(groups)
mgxs_hdf5.add_library(mgxs_lib)
mgxs_hdf5.export_to_hdf5(“my_mgxs.h5”)

I face an attribute error. Back end files of OpenMC tells me that MGXSLibrary is valid and can be used. If this method is not exist for real what should I do to write an hdf5 file of the library I am creating?