Hello guys , I have the following code:

                mail_pool = self.pool['mail.mail']

                data_pool = self.pool['ir.model.data']

                template_xmlid = 'holidays_email_template_a_manager_aprobar'

                template_pool = self.pool.get('mail.template')

                template_id = data_pool.get_object_reference(cr, uid, 'hr_holidays', template_xmlid)

                for attendee in self.browse(cr, uid, ids, context=context):

                    template_pool.send_mail(cr, uid, template_id, attendee.department_id.manager_id.user_id.email,

context=context)

But when I try to send email I have this error:

ValueError: "Expected singleton: mail.template(u'mail.template', 24)" while evaluating
u'holidays_confirm()'

Could someone help me? Thank you!