How to use the polib._POFileParser function in polib

action="store_true",
    )
    (options, args) = optparser.parse_args()

    if options.doctest:
        import os

        if "TERM" in os.environ:
            del os.environ["TERM"]
        import doctest

        failures, tests = doctest.testmod()
        sys.exit(failures and 1 or 0)

    # replace polib._POFileParser to show linenum of problematic msgstr
    class ExtPOFileParser(polib._POFileParser):
        def process(self, symbol, linenum):
            super(ExtPOFileParser, self).process(symbol, linenum)
            if symbol == "MS":  # msgstr
                self.current_entry.linenum = linenum

    polib._POFileParser = ExtPOFileParser

    detected = []
    warning = options.warning
    for f in args:
        detected.extend(
            (f, pe, errors) for pe, errors in check(polib.pofile(f), warning=warning)
        )
    if detected:
        for f, pe, errors in detected:
            for level, checker, error in errors:

if "TERM" in os.environ:
            del os.environ["TERM"]
        import doctest

        failures, tests = doctest.testmod()
        sys.exit(failures and 1 or 0)

    # replace polib._POFileParser to show linenum of problematic msgstr
    class ExtPOFileParser(polib._POFileParser):
        def process(self, symbol, linenum):
            super(ExtPOFileParser, self).process(symbol, linenum)
            if symbol == "MS":  # msgstr
                self.current_entry.linenum = linenum

    polib._POFileParser = ExtPOFileParser

    detected = []
    warning = options.warning
    for f in args:
        detected.extend(
            (f, pe, errors) for pe, errors in check(polib.pofile(f), warning=warning)
        )
    if detected:
        for f, pe, errors in detected:
            for level, checker, error in errors:
                sys.stderr.write(
                    "%s:%d:%s(%s): %s\n" % (f, pe.linenum, level, checker, error)
                )
        sys.exit(1)

def po_to_unicode(po_obj):
    """
    Turns a polib :class:`polib.PoFile` or a :class:`polib.PoEntry` 
    into a :class:`unicode` string.
    
    :param po_obj: Either a :class:`polib.PoFile` or :class:`polib.PoEntry`.
    :rtype: :class:`unicode` string.
    """
    po_text = po_obj.__str__()
    if type(po_text) != types.UnicodeType:
        po_text = po_text.decode('utf-8')
    
    return po_text
    
class PoStream(polib._POFileParser):
    """
    Create a POFile object from a :class:`~StringIO.StringIO`
    instead of a file name or handle.::
    
        import codecs
        from StringIO import StringIO
        
        po_string = codecs.open('sompofile.po', 'r', 'utf-8').read()
        po_file_from_string = PoStream(StringIO(po_string)).parse()
        
        unicode(po_file_from_string)
    
    """
    
    def __init__(self, stream, fpath=None, encoding='utf-8', wrapwidth=78):
        """a pofileparser that can read from a stream"""