old_contents: # nif.py - functions for handling Portuguese 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
  
  """NIF (Número de identificação fiscal, Portuguese VAT number).
  
  The NIF (Número de identificação fiscal, NIPC, Número de Identificação de
  Pessoa Colectiva) is used for VAT purposes. It is a 9-digit number with a
  simple checksum.
  
  >>> compact('PT 501 964 843')
  '501964843'
  >>> is_valid('PT 501 964 843')
  True
  >>> is_valid('PT 501 964 842')  # invalid check digits
  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('PT'):
          number = number[2:]
      return number
  
  
  def calc_check_digit(number):
      """Calculate the check digit. The number passed should not have the
      check digit included."""
      return str((11 - sum((9 - i) * int(n) for i, n in enumerate(number)) ) % 11 % 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) == 9 and \
             number[0] != '0' and calc_check_digit(number[:-1]) == number[-1]
  
new_contents: # nif.py - functions for handling Portuguese 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
  
  """NIF (Número de identificação fiscal, Portuguese VAT number).
  
  The NIF (Número de identificação fiscal, NIPC, Número de Identificação de
  Pessoa Colectiva) is used for VAT purposes. It is a 9-digit number with a
  simple checksum.
  
  >>> validate('PT 501 964 843')
  '501964843'
  >>> validate('PT 501 964 842')  # invalid check digits
  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('PT'):
          number = number[2:]
      return number
  
  
  def calc_check_digit(number):
      """Calculate the check digit. The number passed should not have the
      check digit included."""
      return str((11 - sum((9 - i) * int(n) for i, n in enumerate(number)) ) % 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() or number[0] == '0':
          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: Implement validate() for Portuguese VAT numbers