add possibility to specify a maturity date

# This file is part of Tryton. The COPYRIGHT file at the top level of

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

from decimal import Decimal

from datetime import timedelta

from trytond.config import config

from trytond.i18n import gettext

from trytond.model import Workflow, ModelView, ModelSQL, fields, Unique

        required=True,

        ondelete='RESTRICT',

        help="The revenue account that is used for the fee.")

    maturity_delay = fields.TimeDelta("Maturity Delay",

        required=True,

        help="The period of time after the membership fees must be paid")

    company = fields.Many2One('company.company', 'Company', required=True,

        select=True,

        domain=[

    def default_company(cls):

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

    @classmethod

    def default_maturity_delay(cls):

        return timedelta(0)

class Membership(ModelSQL, ModelView):

    """Membership"""

        party = None

        if account.party_required:

            party = self.member.party

        else:

            party = None

        maturity_date= self.period.start_date + \

            self.period.membership_type.maturity_delay

        return MoveLine(

            debit=abs(amount) if amount > 0 else 0,

            credit=abs(amount) if amount < 0 else 0,

            account=account,

            maturity_date=maturity_date,

            party=party,

        )

            <field name="account_revenue" />

            <label name="journal" />

            <field name="journal" />

            <label name="maturity_delay" />

            <field name="maturity_delay" />

        </page>

    </notebook>

</form>

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