def _get_contracts_list(self, employee):
        '''Return list of contracts in chronological order'''

        contracts = []
        for c in employee.contract_ids:
            l = len(contracts)
            if l == 0:
                contracts.append(c)
            else:
                dCStart = datetime.strptime(c.date_start, OE_DATEFORMAT).date()
                i = l - 1
                while i >= 0:
                    dContractStart = datetime.strptime(
                        contracts[i].date_start, OE_DATEFORMAT).date()
                    if dContractStart < dCStart:
                        contracts = contracts[:i + 1] + [c] + contracts[i + 1:]
                        break
                    elif i == 0:
                        contracts = [c] + contracts
                    i -= 1

        return contracts