old_contents: # vat.py - functions for handling Greek 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
  
  """FPA, ΦΠΑ (Foros Prostithemenis Aksias, the Greek VAT number).
  
  The FPA is a 9-digit number with a simple checksum.
  
  >>> compact('GR 23456783')
  '023456783'
  >>> validate('EL 094259216 ')
  '094259216'
  >>> validate('EL 123456781')
  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('EL') or number.startswith('GR'):
          number = number[2:]
      if len(number) == 8:
          number = '0' + number  # old format had 8 digits
      return number
  
  
  def calc_check_digit(number):
      """Calculate the check digit. The number passed should not have the
      check digit included."""
      checksum = 0
      for n in number:
          checksum = checksum * 2 + int(n)
      return str(checksum * 2 % 11 % 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) != 9:
          raise InvalidLength()
      if calc_check_digit(number[:-1]) != number[-1]:
          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
  
new_contents: # vat.py - functions for handling Greek 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
  
  """FPA, ΦΠΑ, ΑΦΜ (Αριθμός Φορολογικού Μητρώου, the Greek VAT number).
  
  The FPA is a 9-digit number with a simple checksum.
  
  >>> compact('GR 23456783')
  '023456783'
  >>> validate('EL 094259216 ')
  '094259216'
  >>> validate('EL 123456781')
  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('EL') or number.startswith('GR'):
          number = number[2:]
      if len(number) == 8:
          number = '0' + number  # old format had 8 digits
      return number
  
  
  def calc_check_digit(number):
      """Calculate the check digit. The number passed should not have the
      check digit included."""
      checksum = 0
      for n in number:
          checksum = checksum * 2 + int(n)
      return str(checksum * 2 % 11 % 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) != 9:
          raise InvalidLength()
      if calc_check_digit(number[:-1]) != number[-1]:
          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: Change description of Greek FPA number