old_contents: # tfn.py - functions for handling Australian Tax File Numbers (TFNs)
  #
  # Copyright (C) 2016 Vincent Bastos
  # Copyright (C) 2016 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
  
  """TFN (Australian Tax File Number).
  
  The Tax File Number (TFN) is issued by the Australian Taxation Office (ATO)
  to taxpaying individuals and organisations. A business has both a TFN and an
  Australian Business Number (ABN).
  
  The number consists of 8 (older numbers) or 9 digits and includes a check
  digit but otherwise without structure.
  
  More information:
  
  * https://en.wikipedia.org/wiki/Tax_file_number
  * https://www.ato.gov.au/Individuals/Tax-file-number/
  
  >>> validate('123 456 782')
  '123456782'
  >>> validate('999 999 999')
  Traceback (most recent call last):
      ...
  InvalidChecksum: ...
  >>> format('123456782')
  '123 456 782'
  """
  
  import operator
  
  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."""
      return clean(number, ' ').strip()
  
  
  def checksum(number):
      """Calculate the checksum."""
      weights = (1, 4, 3, 7, 5, 8, 6, 9, 10)
      return sum(w * int(n) for w, n in zip(weights, number)) % 11
  
  
  def validate(number):
      """Checks to see if the number provided is a valid TFN. This checks the
      length, formatting and check digit."""
      number = compact(number)
      if not number.isdigit():
          raise InvalidFormat()
      if len(number) not in (8, 9):
          raise InvalidLength()
      if checksum(number) != 0:
          raise InvalidChecksum()
      return number
  
  
  def is_valid(number):
      """Checks to see if the number provided is a valid TFN. This checks the
      length, formatting and check digit."""
      try:
          return bool(validate(number))
      except ValidationError:
          return False
  
  
  def format(number):
      """Reformat the passed number to the standard format."""
      number = compact(number)
      return ' '.join((number[0:3], number[3:6], number[6:]))
  
new_contents: # tfn.py - functions for handling Australian Tax File Numbers (TFNs)
  #
  # Copyright (C) 2016 Vincent Bastos
  # Copyright (C) 2016 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
  
  """TFN (Australian Tax File Number).
  
  The Tax File Number (TFN) is issued by the Australian Taxation Office (ATO)
  to taxpaying individuals and organisations. A business has both a TFN and an
  Australian Business Number (ABN).
  
  The number consists of 8 (older numbers) or 9 digits and includes a check
  digit but otherwise without structure.
  
  More information:
  
  * https://en.wikipedia.org/wiki/Tax_file_number
  * https://www.ato.gov.au/Individuals/Tax-file-number/
  
  >>> validate('123 456 782')
  '123456782'
  >>> validate('999 999 999')
  Traceback (most recent call last):
      ...
  InvalidChecksum: ...
  >>> format('123456782')
  '123 456 782'
  """
  
  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."""
      return clean(number, ' ').strip()
  
  
  def checksum(number):
      """Calculate the checksum."""
      weights = (1, 4, 3, 7, 5, 8, 6, 9, 10)
      return sum(w * int(n) for w, n in zip(weights, number)) % 11
  
  
  def validate(number):
      """Checks to see if the number provided is a valid TFN. This checks the
      length, formatting and check digit."""
      number = compact(number)
      if not number.isdigit():
          raise InvalidFormat()
      if len(number) not in (8, 9):
          raise InvalidLength()
      if checksum(number) != 0:
          raise InvalidChecksum()
      return number
  
  
  def is_valid(number):
      """Checks to see if the number provided is a valid TFN. This checks the
      length, formatting and check digit."""
      try:
          return bool(validate(number))
      except ValidationError:
          return False
  
  
  def format(number):
      """Reformat the passed number to the standard format."""
      number = compact(number)
      return ' '.join((number[0:3], number[3:6], number[6:]))
  
subject: Remove unused import