old_contents: # The MIT License
  #
  # Copyright (c) 2009 Andreas Stuehrk
  #
  # Permission is hereby granted, free of charge, to any person obtaining a copy
  # of this software and associated documentation files (the "Software"), to deal
  # in the Software without restriction, including without limitation the rights
  # to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  # copies of the Software, and to permit persons to whom the Software is
  # furnished to do so, subject to the following conditions:
  #
  # The above copyright notice and this permission notice shall be included in
  # all copies or substantial portions of the Software.
  #
  # 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 OR COPYRIGHT HOLDERS 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.
  
  
  import curses
  import errno
  import os
  import pydoc
  import subprocess
  import sys
  
  
  def get_pager_command():
      command = os.environ.get('PAGER', 'less -r').split()
      return command
  
  
  def page_internal(data):
      """A more than dumb pager function."""
      if hasattr(pydoc, 'ttypager'):
          pydoc.ttypager(data)
      else:
          sys.stdout.write(data)
  
  
  def page(data, use_internal=False):
      command = get_pager_command()
      if not command or use_internal:
          page_internal(data)
      else:
          curses.endwin()
          try:
              popen = subprocess.Popen(command, stdin=subprocess.PIPE)
              popen.stdin.write(data)
              popen.stdin.close()
          except OSError, e:
              if e.errno == errno.ENOENT:
                  # pager command not found, fall back to internal pager
                  page_internal(data)
                  return
              if e.errno != errno.EPIPE:
                  raise
          while True:
              try:
                  popen.wait()
              except OSError, e:
                  if e.errno != errno.EINTR:
                      raise
              else:
                  break
          curses.doupdate()
  
new_contents: # The MIT License
  #
  # Copyright (c) 2009 Andreas Stuehrk
  #
  # Permission is hereby granted, free of charge, to any person obtaining a copy
  # of this software and associated documentation files (the "Software"), to deal
  # in the Software without restriction, including without limitation the rights
  # to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  # copies of the Software, and to permit persons to whom the Software is
  # furnished to do so, subject to the following conditions:
  #
  # The above copyright notice and this permission notice shall be included in
  # all copies or substantial portions of the Software.
  #
  # 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 OR COPYRIGHT HOLDERS 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.
  
  
  import curses
  import errno
  import os
  import pydoc
  import subprocess
  import sys
  
  
  def get_pager_command():
      command = os.environ.get('PAGER', 'less -r').split()
      return command
  
  
  def page_internal(data):
      """A more than dumb pager function."""
      if hasattr(pydoc, 'ttypager'):
          pydoc.ttypager(data)
      else:
          sys.stdout.write(data)
  
  
  def page(data, use_internal=False):
      command = get_pager_command()
      if not command or use_internal:
          page_internal(data)
      else:
          curses.endwin()
          try:
              popen = subprocess.Popen(command, stdin=subprocess.PIPE)
              if isinstance(data, unicode):
                  data = data.encode(sys.__stdout__.encoding, 'replace')
              popen.stdin.write(data)
              popen.stdin.close()
          except OSError, e:
              if e.errno == errno.ENOENT:
                  # pager command not found, fall back to internal pager
                  page_internal(data)
                  return
              if e.errno != errno.EPIPE:
                  raise
          while True:
              try:
                  popen.wait()
              except OSError, e:
                  if e.errno != errno.EINTR:
                      raise
              else:
                  break
          curses.doupdate()
  
subject: Make pager work with Python 3.