Add a input socket with python

Coding Python Support
1

I have created a output node with this code:

import bpy


matname = "MyMat"
mat = bpy.data.materials.new(matname)
mat.use_nodes = True
nodes = mat.node_tree.nodes


# Remove all Nodes
for node in mat.node_tree.nodes:
    mat.node_tree.nodes.remove(node)


# New node
node = nodes.new('NodeGroupOutput')
node.name = 'Group Output'
node.is_active_output = True
node.inputs[0].name = 'My Value 1'
# I need add a new socket here, but HOW?
# node.inputs.new('OUT','My Value 2')
node.inputs[1].name = 'My Value 2'

But I cannot add the second socket. can anyone help me?

Note: I have solved creating the input/output at Group level, not node level.