def _versions(self, versions):
if versions and (set(versions) - set(commands.versions(self.version))):
raise StompProtocolError('Invalid versions: %s [version=%s]' % (versions, self.version))
self.__versions = versions
def _versions(self):
try:
self.__versions
except:
self.__versions = None
return list(sorted(self.__versions or commands.versions(self.version)))