odoo sequence set via python code

odoo_seq.py

class SaleDoc(models.Model):
    _name = 'sale.doc'

    name = fields.Char('No Dokumen')
    tanggal = fields.Date('Tanggal')
    sale_id = fields.Many2one('sale.order', string="Order")
    keterangan = fields.Text('Keterangan')
    file = fields.Binary('File Dokumen')

#     Magic suppose to be happen in here. NOT BUGS
    @api.model
    def create(self, vals):
#       1 GET YOUR SEQUENCE WITH LATEST INCREMENT RUNNING NUMBER
        seq = self.env['ir.sequence'].next_by_code('sale.doc') or '/'
#       2 SET THE SEQUENCE ON 'NAME' FIELD
        vals['name'] = seq
#       3 RETURN SUPER TO EXTEND THE CREATE METHOD 
        return super(SaleDoc, self).create(vals)