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# vat.py - functions for handling German 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
"""Ust ID Nr. (Umsatzsteur Identifikationnummer, German VAT number).
The number is 10 digits long and uses the ISO 7064 Mod 11, 10 check digit
algorithm.
>>> compact('DE 136,695 976')
'136695976'
>>> validate('DE136695976')
'136695976'
>>> validate('136695978')
Traceback (most recent call last):
...
InvalidChecksum: ...
"""
from stdnum.exceptions import *
from stdnum.iso7064 import mod_11_10
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('DE'):
number = number[2:]
return number
def validate(number):
"""Check if the number provided is a valid VAT number. This checks the
length, formatting and check digit."""
number = compact(number)
if not number.isdigit() or number[0] == '0':
raise InvalidFormat()
if len(number) != 9:
raise InvalidLength()
mod_11_10.validate(number)
return number
def is_valid(number):
"""Check if the number provided is a valid VAT number. This checks the
length, formatting and check digit."""
try:
return bool(validate(number))
except ValidationError:
return False
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