def _write_comment(comment, prefix=''):
     # xgettext always wraps comments even if --no-wrap is passed;
     # provide the same behaviour
     if width and width > 0:
         _width = width
     else:
         _width = 76
     for line in wraptext(comment, _width):
         _write('#%s %s\n' % (prefix, line.strip()))

def write_po(fileobj, catalog, width=76, no_location=False, omit_header=False,
             sort_output=False, sort_by_file=False, ignore_obsolete=False,
             include_previous=False):
    r"""Write a ``gettext`` PO (portable object) template file for a given
    message catalog to the provided file-like object.

    >>> catalog = Catalog()
    >>> catalog.add(u'foo %(name)s', locations=[('main.py', 1)],
    ...             flags=('fuzzy',))
    <Message...>
    >>> catalog.add((u'bar', u'baz'), locations=[('main.py', 3)])
    <Message...>
    >>> from io import BytesIO
    >>> buf = BytesIO()
    >>> write_po(buf, catalog, omit_header=True)
    >>> print buf.getvalue()
    #: main.py:1
    #, fuzzy, python-format
    msgid "foo %(name)s"
    msgstr ""
    <BLANKLINE>
    #: main.py:3
    msgid "bar"
    msgid_plural "baz"
    msgstr[0] ""
    msgstr[1] ""
    <BLANKLINE>
    <BLANKLINE>

    :param fileobj: the file-like object to write to
    :param catalog: the `Catalog` instance
    :param width: the maximum line width for the generated output; use `None`,
                  0, or a negative number to completely disable line wrapping
    :param no_location: do not emit a location comment for every message
    :param omit_header: do not include the ``msgid ""`` entry at the top of the
                        output
    :param sort_output: whether to sort the messages in the output by msgid
    :param sort_by_file: whether to sort the messages in the output by their
                         locations
    :param ignore_obsolete: whether to ignore obsolete messages and not include
                            them in the output; by default they are included as
                            comments
    :param include_previous: include the old msgid as a comment when
                             updating the catalog
    """
    def _normalize(key, prefix=''):
        return normalize(key, prefix=prefix, width=width)

    def _write(text):
        if isinstance(text, text_type):
            text = text.encode(catalog.charset, 'backslashreplace')
        fileobj.write(text)

    def _write_comment(comment, prefix=''):
        # xgettext always wraps comments even if --no-wrap is passed;
        # provide the same behaviour
        if width and width > 0:
            _width = width
        else:
            _width = 76
        for line in wraptext(comment, _width):
            _write('#%s %s\n' % (prefix, line.strip()))

    def _write_message(message, prefix=''):
        if isinstance(message.id, (list, tuple)):
            if message.context:
                _write('%smsgctxt %s\n' % (prefix,
                                           _normalize(message.context, prefix)))
            _write('%smsgid %s\n' % (prefix, _normalize(message.id[0], prefix)))
            _write('%smsgid_plural %s\n' % (
                prefix, _normalize(message.id[1], prefix)
            ))

            for idx in range(catalog.num_plurals):
                try:
                    string = message.string[idx]
                except IndexError:
                    string = ''
                _write('%smsgstr[%d] %s\n' % (
                    prefix, idx, _normalize(string, prefix)
                ))
        else:
            if message.context:
                _write('%smsgctxt %s\n' % (prefix,
                                           _normalize(message.context, prefix)))
            _write('%smsgid %s\n' % (prefix, _normalize(message.id, prefix)))
            _write('%smsgstr %s\n' % (
                prefix, _normalize(message.string or '', prefix)
            ))

    messages = list(catalog)
    if sort_output:
        messages.sort()
    elif sort_by_file:
        messages.sort(lambda x,y: cmp(x.locations, y.locations))

    for message in messages:
        if not message.id: # This is the header "message"
            if omit_header:
                continue
#.........这里部分代码省略.........

 def _write_comment(comment, prefix=''):
     lines = comment
     if width and width > 0:
         lines = wraptext(comment, width)
     for line in lines:
         _write('#%s %s\n' % (prefix, line.strip()))