type = lua_gettable(L, -2);
lua_ensure(type == LUA_TSTRING || type == LUA_TNUMBER,
"Attribute 'bandwidth' must be specified for backbone and must either be a string (in the right format; see docs) or a number.");
type = lua_gettable(L, -2);
lua_ensure(type == LUA_TSTRING || type == LUA_TNUMBER,
"Attribute 'bandwidth' must be specified for backbone and must either be a string (in the right format; see docs) or a number.");