'Add the operating_system class object into the
platform.operating_sys dictionary'

def add_operating_system(self, name, os_class):

    if (name in Platform.reserved_oss):
        raise ValueError(('%s    is    a    spack    reserved    alias    and    cannot    be    the    name    of    an    OS' % name))
    self.operating_sys[name] = os_class
