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# btw.py - functions for handling Dutch VAT numbers
#
# Copyright (C) 2012, 2013 Arthur de Jong
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2.1 of the License, or (at your option) any later version.
#
# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
# 02110-1301 USA
"""Btw-nummer (Omzetbelastingnummer, the Dutch VAT number).
The btw-nummer is the Dutch number for VAT. It consists of a RSIN or BSN
followed by the letter B and two digits that identify the unit within the
organisation (usually 01).
More information:
* https://en.wikipedia.org/wiki/VAT_identification_number
* https://nl.wikipedia.org/wiki/Btw-nummer_(Nederland)
>>> validate('004495445B01')
'004495445B01'
>>> validate('NL4495445B01')
'004495445B01'
>>> validate('123456789B90')
Traceback (most recent call last):
...
InvalidChecksum: ...
"""
from stdnum.exceptions import *
from stdnum.nl import bsn
from stdnum.util import clean
def compact(number):
"""Convert the number to the minimal representation. This strips the
number of any valid separators and removes surrounding whitespace."""
number = clean(number, ' -.').upper().strip()
if number.startswith('NL'):
number = number[2:]
return bsn.compact(number[:-3]) + number[-3:]
def validate(number):
"""Check if the number is a valid BTW number. This checks the length,
formatting and check digit."""
number = compact(number)
if not number[10:].isdigit() or int(number[10:]) <= 0:
raise InvalidFormat()
if len(number) != 12:
raise InvalidLength()
if number[9] != 'B':
raise InvalidFormat()
bsn.validate(number[:9])
return number
def is_valid(number):
"""Check if the number is a valid BTW number."""
try:
return bool(validate(number))
except ValidationError:
return False
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