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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def add_vlan_to_interface(self, interface, vlan_id):
 """Add vlan interface. ip link add link eth0 name eth0.10 type vlan id 10 """

        subif = '%s.%s' % (interface, vlan_id)
        vlan_id = '%s' % vlan_id
        cmd = ['ip', 'link', 'add', 'link', interface, 'name',
               subif, 'type', 'vlan', 'id', vlan_id]
        stdcode, stdout = agent_utils.execute(cmd, root=True)
        if stdcode == 0:
            return agent_utils.make_response(code=stdcode)
        # execute failed.
        message = stdout.pop(0)
        return agent_utils.make_response(code=stdcode, message=message)