New in version 2.3.
This module provides a single function:
| path, name) | 
from pkgutil import extend_path __path__ = extend_path(__path__, __name__)
This will add to the package's __path__ all subdirectories of
  directories on sys.path named after the package.  This is
  useful if one wants to distribute different parts of a single
  logical package as multiple directories.
It also looks for *.pkg files beginning where *
  matches the name argument.  This feature is similar to
  *.pth files (see the site module for more
  information), except that it doesn't special-case lines starting
  with import.  A *.pkg file is trusted at face value:
  apart from checking for duplicates, all entries found in a
  *.pkg file are added to the path, regardless of whether they
  exist the filesystem.  (This is a feature.)
If the input path is not a list (as is the case for frozen packages) it is returned unchanged. The input path is not modified; an extended copy is returned. Items are only appended to the copy at the end.
It is assumed that sys.path is a sequence.  Items of
  sys.path that are not (Unicode or 8-bit) strings referring to
  existing directories are ignored.  Unicode items on sys.path
  that cause errors when used as filenames may cause this function to
  raise an exception (in line with os.path.isdir() behavior).