old_contents: ## This file is part of Invenio.
  ## Copyright (C) 2013 CERN.
  ##
  ## Invenio is free software; you can redistribute it and/or
  ## modify it under the terms of the GNU General Public License as
  ## published by the Free Software Foundation; either version 2 of the
  ## License, or (at your option) any later version.
  ##
  ## Invenio 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
  ## General Public License for more details.
  ##
  ## You should have received a copy of the GNU General Public License
  ## along with Invenio; if not, write to the Free Software Foundation, Inc.,
  ## 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
  
  
  def _convert_x_to_10(x):
      if x != 'X':
          return int(x)
      else:
          return 10
  
  
  def is_type_isbn10(val):
      """
      Test if argument is an ISBN-10 number
  
      Courtesy Wikipedia:
      http://en.wikipedia.org/wiki/International_Standard_Book_Number
      """
      val = val.replace("-", "").replace(" ", "")
      if len(val) != 10:
          return False
      r = sum([(10 - i) * (_convert_x_to_10(x)) for i, x in enumerate(val)])
      return not (r % 11)
  
  
  def is_type_isbn13(val):
      """
      Test if argument is an ISBN-13 number
  
      Courtesy Wikipedia:
      http://en.wikipedia.org/wiki/International_Standard_Book_Number
      """
      val = val.replace("-", "").replace(" ", "")
      if len(val) != 13:
          return False
      total = sum([int(num) * weight for num, weight in zip(val, (1, 3) * 6)])
      ck = (10 - total) % 10
      return ck == int(val[-1])
  
  
  def is_type_isbn(val):
      """ Test if argument is an ISBN-10 or ISBN-13 number """
      return is_type_isbn10(val) or is_type_isbn13(val)
  
new_contents: ## This file is part of Invenio.
  ## Copyright (C) 2013 CERN.
  ##
  ## Invenio is free software; you can redistribute it and/or
  ## modify it under the terms of the GNU General Public License as
  ## published by the Free Software Foundation; either version 2 of the
  ## License, or (at your option) any later version.
  ##
  ## Invenio 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
  ## General Public License for more details.
  ##
  ## You should have received a copy of the GNU General Public License
  ## along with Invenio; if not, write to the Free Software Foundation, Inc.,
  ## 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
  
  
  def _convert_x_to_10(x):
      if x != 'X':
          return int(x)
      else:
          return 10
  
  
  def is_type_isbn10(val):
      """
      Test if argument is an ISBN-10 number
  
      Courtesy Wikipedia:
      http://en.wikipedia.org/wiki/International_Standard_Book_Number
      """
      val = val.replace("-", "").replace(" ", "")
      if len(val) != 10:
          return False
      r = sum([(10 - i) * (_convert_x_to_10(x)) for i, x in enumerate(val)])
      return not (r % 11)
  
  
  def is_type_isbn13(val):
      """
      Test if argument is an ISBN-13 number
  
      Courtesy Wikipedia:
      http://en.wikipedia.org/wiki/International_Standard_Book_Number
      """
      val = val.replace("-", "").replace(" ", "")
      if len(val) != 13:
          return False
      total = sum([int(num) * weight for num, weight in zip(val, (1, 3) * 6)])
      ck = (10 - total) % 10
      return ck == int(val[-1])
  
  
  def is_type_isbn(val):
      """ Test if argument is an ISBN-10 or ISBN-13 number """
      try:
          return is_type_isbn10(val) or is_type_isbn13(val)
      except:
          return False
  
subject: fix for `is_type_isbn`