locals

isPosix = os.name == 'posix'
isNt = os.name == 'nt'
isWin9x = os.name == 'win9x'
isMac = os.name == 'macos'

if isPosix:
  do_posix_version()
elif isNt:
  do_window_version()
elif isWin9x:
  do_old_windows_version()
elif isMac:
  do_mac_os_version()

if isPosix or isNt or isWin9x or isMac:
  print "I did it"
else:
  print "Operating system unsupported"

original

if os.name == 'posix':
  do_posix_version()
elif os.name == 'nt':
  do_window_version()
elif os.name == 'win9x':
  do_old_windows_version()
elif os.name == 'macos':
  do_mac_os_version()
any:
  print "I did it"
else:
  print "Operating system unsupported"