workcenter_pool = self.pool.get('mrp.production.workcenter.line')
for workcenter_line in obj.workcenter_lines:
if workcenter_line.state == 'draft':
workcenter_line.signal_workflow('button_start_working')
workcenter_line.signal_workflow('button_done')
workcenter_pool = self.pool.get('mrp.production.workcenter.line')
for workcenter_line in obj.workcenter_lines:
if workcenter_line.state == 'draft':
workcenter_line.signal_workflow('button_start_working')
workcenter_line.signal_workflow('button_done')