applying ced and pokoli's suggestion

# this repository contains the full copyright notices and license terms.

from trytond.model import ModelView, ModelSQL, ModelSingleton, fields

from trytond.pyson import Eval

from trytond.pool import Pool

from trytond.modules.company.model import (CompanyMultiValueMixin,

                                           CompanyValueMixin)

            ],

            help="Used to generate the number given to association members."))

    @classmethod

    def default_member_sequence(cls, **pattern):

        return getattr(

            cls.multivalue_model('member_sequence'),

            'default_member_sequence', lambda: None)()

class MemberSequence(ModelSQL, CompanyValueMixin):

    """Member Configuration Sequence"""

            ('code', '=', 'association.member'),

        ],

        depends=['company'])

    @classmethod

    def default_member_sequence(cls):

        pool = Pool()

        ModelData = pool.get('ir.model.data')

        try:

            return ModelData.get_id('association', 'sequence_member')

        except KeyError:

            return None

 No newline at end of file

            <field name="group" ref="group_association_admin"/>

        </record>

    </data>

    <data noupdate="1">

        <record model="association.configuration.member_sequence" id="configuration_member_sequence">

            <field name="member_sequence" ref="sequence_member"/>

        </record>

    </data>

</tryton>

    del _states, _depends

    @classmethod

    def default_member_state(cls):

        return 'draft'

    @classmethod

    def validate(cls, memberships):

        super().validate(memberships)

    def on_change_with_member_state(self, name=None):

        if self.member:

            return self.member.state

        else:

            return 'draft'

    @fields.depends('member', '_parent_member.join_date')

    def on_change_with_member_join_date(self, name=None):

    paid = fields.Function(fields.Boolean('paid'), 'is_paid')

    reconciled = fields.Function(fields.Date("Reconciled"), 'get_reconciled')

    amount = fields.Function(fields.Numeric("Amount", fee_digit),

        'on_change_with_amount')

        'on_change_with_amount', searcher='search_amount')

    del _states

    @fields.depends('period', '_parent_period.amount')

    def on_change_with_amount(self, name=None):

        if self.period:

            return self.period.amount

    @classmethod

    def __setup__(cls):

        super().__setup__()

        cls._sql_constraints = [

            ('code_uniq', Unique(table, table.member, table.period),

            gettext('association.msg_period_unique'))

             "The periods for each member must be unique.")

        ]

        cls._buttons.update({

            },

        })

    @fields.depends('period', '_parent_period.amount')

    def on_change_with_amount(self, name=None):

        if self.period:

            return self.period.amount

    @fields.depends('move', '_parent_move.state')

    def on_change_with_move_state(self, name=None):

        if self.move:

    def default_company(cls):

        return Transaction().context.get('company')

    @classmethod

    def search_amount(cls, name, clause):

        return [('period.amount',) + tuple(clause[1:])]

    def get_reconciled(self, name):

        def get_reconciliation(line):

            if line.reconciliation and line.reconciliation.delegate_to:

        <record model="ir.message" id="msg_party_receivable_missing">

            <field name="text">The party "%(party)s" doesn't have an account receivable defined.</field>

        </record>

        <record model="ir.message" id="msg_period_unique">

            <field name="text">The periods for each member must be unique.</field>

        </record>

        <record model="ir.message" id="msg_overlapping_membership">

            <field name="text">The membership "%(first)s" overlaps with the period "%(second)s".</field>

        </record>

    >>> receivable = accounts['receivable']

    >>> payable = accounts['payable']

    >>> revenue = accounts['revenue']

    >>> expense = accounts['expense']

    >>> account_tax = accounts['tax']

    >>> account_cash = accounts['cash']

Create party::

    >>> Party = Model.get('party.party')

    >>> party = Party(name='Party')

    >>> party.account_payable = payable

    >>> party.account_receivable = receivable

    >>> party.save()

Create memberships::

   >>> def periodgen(startDate,deltaTime,quantity):

   ...   firstDate = startDate

   ...   for period in range(quantity):

   ...      lastDate = firstDate + deltaTime

   ...      yield (firstDate,lastDate)

   ...      firstDate = lastDate + datetime.timedelta(days=1)

   >>> Journal = Model.get('account.journal')

   >>> Move = Model.get('account.move')

   >>> journal_revenue, = Journal.find([

   >>> start_date = datetime.date.today()

   >>> timedelta = datetime.timedelta(weeks=4)

   >>> fiscalMonth = 13

   >>> datedeltas = [(start_date + timedelta*(n-1) + datetime.timedelta(days=1),start_date + timedelta*n,f"period {n}") for n in range(1,fiscalMonth+1)]

   >>> periods = [ membership.periods.new(start_date=period[0],end_date=period[1], name=period[2], amount=Decimal(42)) for period in datedeltas ]

   >>> periods = []

   >>> for period in periodgen(start_date,timedelta,fiscalMonth):

   ...   newPeriod = membership.periods.new(

   ...      start_date=period[0],

   ...      end_date=period[1],

   ...      name="test",

   ...      amount=Decimal(42))

   ...   periods.append(newPeriod)

   >>> membership.save()

Create member::

   >>> Period = Model.get('association.membership.period')

   >>> Fee = Model.get('association.membership.fee')

   >>> period, = Period.find(["name","=","period 1"])

   >>> period = Period.find([])[0]

   >>> fee = Fee(member=member,period=period)

   >>> fee.save() #doctest: +IGNORE_EXCEPTION_DETAIL

   Traceback (most recent call last):

   >>> Period = Model.get('association.membership.period')

   >>> Fee = Model.get('association.membership.fee')

   >>> period, = Period.find(["name","=","period 1"])

   >>> period = Period.find([])[0]

   >>> fee = Fee(member=member,period=period)

   >>> fee.save()

   >>> fee.click('post_move')