
This patch is deprecated use xx = [] for the parameter initial value, this parameter will only be initialized at the first call,this is not what we expected. Better choice is to set the initial value to None, then initialize xx with xx= xx or [] in method body. More details:http://effbot.org/zone/default-values.htm Change-Id: Ie538081bb8905ed9b6d5ec5fa75c344a8074fb0e