docs: def _get_home():
      """Find user's home directory if possible.
      Otherwise, returns None.
  
      :see:  http://mail.python.org/pipermail/python-list/2005-February/325395.html
  
      This function is copied from matplotlib version 1.4.3, Jan 2016
      """
      try:
          if six.PY2 and sys.platform == 'win32':
              path = os.path.expanduser(b"~").decode(sys.getfilesystemencoding())
          else:
              path = os.path.expanduser("~")
      except ImportError:
          # This happens on Google App Engine (pwd module is not present).
          pass
      else:
          if os.path.isdir(path):
              return path
      for evar in ('HOME', 'USERPROFILE', 'TMP'):
          path = os.environ.get(evar)
          if path is not None and os.path.isdir(path):
              return path
      return None