'Use OLE property sets to get base properties'

def _get_properties(self, properties):

    try:
        pss = self.stg.QueryInterface(pythoncom.IID_IPropertySetStorage)
    except pythoncom.com_error as e:
        self._trace('No    Property    information    could    be    retrieved', e)
        return
    ps = pss.Open(PSGUID_SUMMARYINFORMATION)
    props = (PIDSI_TITLE, PIDSI_SUBJECT, PIDSI_AUTHOR, PIDSI_KEYWORDS, PIDSI_COMMENTS)
    (title, subject, author, keywords, comments) = ps.ReadMultiple(props)
    if (title is not None):
        properties['title'] = title
    if (subject is not None):
        properties['description'] = subject
    if (author is not None):
        properties['author'] = author
    if (keywords is not None):
        properties['keywords'] = keywords
    if (comments is not None):
        properties['comments'] = comments
