operator_example.py

def sv_main(n_items=1500):

    in_sockets = [['s', 'n_items', n_items]]
    Verts = []

    def func1():
        tree_name = bpy.context.node.id_data.name
        ng = bpy.data.node_groups[tree_name]

        # this will read the first 'Objects in' node in
        # the current tree. if you have several it would
        # be necessary to check the node `label` too.
        obj_in = ng.nodes['Objects_in']
        obj_names = obj_in.get('objects_local', None)
        print(str(obj_names))

    out_sockets = [['v', 'Verts', [Verts]]]
    ui_operators = [['print_names', func1]]

    return in_sockets, out_sockets, ui_operators