simgrid::s4u::Host* host = simgrid::s4u::Host::by_name_or_null(elm.second);
xbt_assert(host, "Host %s undefined", elm.second.c_str());
simgrid::s4u::Host* host = simgrid::s4u::Host::by_name_or_null(elm.second);
xbt_assert(host, "Host %s undefined", elm.second.c_str());