old_contents: # anum.py - functions for handling Hungarian VAT numbers
  # coding: utf-8
  #
  # Copyright (C) 2012 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
  
  """ANUM (Közösségi adószám, Hungarian VAT number).
  
  The ANUM is the Hungarian VAT (Közösségi adószám) number. It is an 8-digit
  taxpayer registration number that includes a weighted checksum.
  
  >>> compact('HU-12892312')
  '12892312'
  >>> is_valid('HU-12892312')
  True
  >>> is_valid('HU-12892313')  # invalid check digit
  False
  """
  
  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('HU'):
          number = number[2:]
      return number
  
  
  def checksum(number):
      """Calculate the checksum. Valid numbers should have a checksum of 0."""
      weights = (9, 7, 3, 1, 9, 7, 3, 1)
      return sum(weights[i] * int(n) for i, n in enumerate(number)) % 10
  
  
  def is_valid(number):
      """Checks to see if the number provided is a valid VAT number. This
      checks the length, formatting and check digit."""
      try:
          number = compact(number)
      except:
          return False
      return number.isdigit() and len(number) == 8 and checksum(number) == 0
  
new_contents: # anum.py - functions for handling Hungarian VAT numbers
  # coding: utf-8
  #
  # 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
  
  """ANUM (Közösségi adószám, Hungarian VAT number).
  
  The ANUM is the Hungarian VAT (Közösségi adószám) number. It is an 8-digit
  taxpayer registration number that includes a weighted checksum.
  
  >>> validate('HU-12892312')
  '12892312'
  >>> validate('HU-12892313')  # invalid check digit
  Traceback (most recent call last):
      ...
  InvalidChecksum: ...
  """
  
  from stdnum.exceptions import *
  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('HU'):
          number = number[2:]
      return number
  
  
  def checksum(number):
      """Calculate the checksum. Valid numbers should have a checksum of 0."""
      weights = (9, 7, 3, 1, 9, 7, 3, 1)
      return sum(weights[i] * int(n) for i, n in enumerate(number)) % 10
  
  
  def validate(number):
      """Checks to see if the number provided is a valid VAT number. This
      checks the length, formatting and check digit."""
      number = compact(number)
      if not number.isdigit():
          raise InvalidFormat()
      if len(number) != 8:
          raise InvalidLength()
      if checksum(number) != 0:
          raise InvalidChecksum()
      return number
  
  
  def is_valid(number):
      """Checks to see 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
  
subject: Implement validate() for Hungarian numbers