text: #!/usr/bin/env python
  #
  # Public Domain 2014-2015 MongoDB, Inc.
  # Public Domain 2008-2014 WiredTiger, Inc.
  #
  # This is free and unencumbered software released into the public domain.
  #
  # Anyone is free to copy, modify, publish, use, compile, sell, or
  # distribute this software, either in source code form or as a compiled
  # binary, for any purpose, commercial or non-commercial, and by any
  # means.
  #
  # In jurisdictions that recognize copyright laws, the author or authors
  # of this software dedicate any and all copyright interest in the
  # software to the public domain. We make this dedication for the benefit
  # of the public at large and to the detriment of our heirs and
  # successors. We intend this dedication to be an overt act of
  # relinquishment in perpetuity of all present and future rights to this
  # software under copyright law.
  #
  # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  # EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  # MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
  # IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
  # OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  # ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  # OTHER DEALINGS IN THE SOFTWARE.
  #
  
  from packing import pack, unpack
  
  def check_common(fmt, verbose, *v):
      v = list(v)
      packed = pack(fmt, *v)
      unpacked = unpack(fmt, packed)
      if unpacked == v:
          result = 'ok'
      else:
          result = '** FAIL!'
      print '* %s as %s: %s' % (repr(v), fmt, result)
      if verbose or unpacked != v:
          print '** packed: ', ''.join('%02x' % ord(c) for c in packed)
          print '** unpacked: ', unpacked
  
  def check(fmt, *v):
      check_common(fmt, False, *v)
  
  def check_verbose(fmt, *v):
      check_common(fmt, True, *v)
  
  
  if __name__ == '__main__':
      import sys
      if 'verbose' in sys.argv:
          check = check_verbose
      check('iii', 0, 101, -99)
      check('3i', 0, 101, -99)
      check('iS', 42, "forty two")
  
      #
      check('S', 'abc')
      check('9S', 'a' * 9)
      check('9SS', "forty two", "spam egg")
      check('42S', 'a' * 42)
      check('42SS', 'a' * 42, 'something')
      check('S42S', 'something', 'a' * 42)
      # nul terminated string with padding
      check('10SS', 'aaaaa\x00\x00\x00\x00\x00', 'something')
      check('S10S', 'something', 'aaaaa\x00\x00\x00\x00\x00')
  
      check('u', r"\x42" * 20)
      check('uu', r"\x42" * 10, r"\x42" * 10)
      check('3u', r"\x4")
      check('3uu', r"\x4", r"\x42" * 10)
      check('u3u', r"\x42" * 10, r"\x4")
  
      check('s', "4")
      check("2s", "42")
  