docs: def open (filename, mode='r', **options):
      """Returns an instance of a :class:`PCapStream` class which contains
      the ``read()``, ``write()``, and ``close()`` methods.  Binary mode
      is assumed for this module, so the "b" is not required when
      calling ``open()``.
  
      If the optiontal ``rollover`` parameter is True, a
      :class:`PCapRolloverStream` is created instead.  In that case
      ``filename`` is treated as a ``strftime(3)`` format string and
      ``nbytes``, ``npackets``, ``nseconds``, and ``dryrun`` parameters
      may also be specified.  See :class:``PCapRolloverStream`` for more
      information.
  
      NOTE: :class:`PCapRolloverStream` is always opened in write mode
      ("wb") and supports only ``write()`` and ``close()``, not
      ``read()``.
      """
      mode = mode.replace('b', '') + 'b'
  
      if options.get('rollover', False):
          stream = PCapRolloverStream(filename,
                                      options.get('nbytes'  , None),
                                      options.get('npackets', None),
                                      options.get('nseconds', None),
                                      options.get('dryrun'  , False))
      else:
          stream = PCapStream( __builtin__.open(filename, mode), mode )
  
      return stream