[pox-dev] About libopenflow_01 question (vlan)

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Recently, I am research on openflow to control my virtual machine 
I have question about libopenflow_01:what is @openflow_action 
('OFPAT_SET_VLAN_VID', 1) at class ofp_action_vlan_vidI am so confuse about "1" 
.. is the argument? 
And the other question is that It is possible to create vxlan just like 
ofp_action_vlan_vid to set vxlan VNI ? 
Thanks