How to use the rss2email.config.CONFIG function in rss2email

...     content_type='plain',
    ...     extra_headers={'Approved': 'joe@bob.org'})
    >>> print(message.as_string())  # doctest: +REPORT_UDIFF
    MIME-Version: 1.0
    Content-Type: text/plain; charset="us-ascii"
    Content-Transfer-Encoding: 7bit
    From: John 
    To: =?utf-8?b?zpbOtc+Nz4I=?= 
    Subject: Testing
    Approved: joe@bob.org
    
    Hello, world!
    
    """
    if config is None:
        config = _config.CONFIG
    if section not in config.sections():
        section = 'DEFAULT'
    encodings = [
        x.strip() for x in config.get(section, 'encodings').split(',')]

    # Split real name (which is optional) and email address parts
    sender_name,sender_addr = _parseaddr(sender)
    recipient_list = []
    for recipient_name, recipient_addr in _getaddresses([recipient]):
        recipient_encoding = guess_encoding(recipient_name, encodings)
        recipient_name = str(_Header(recipient_name, recipient_encoding).encode())
        recipient_addr.encode('ascii')
        recipient_list.append(_formataddr((recipient_name, recipient_addr)))

    sender_encoding = guess_encoding(sender_name, encodings)
    recipient_encoding = guess_encoding(recipient_name, encodings)

def sendmail_send(sender, recipient, message, config=None, section='DEFAULT'):
    if config is None:
        config = _config.CONFIG
    message_bytes = _flatten(message)
    sendmail = config.get(section, 'sendmail')
    sender_name,sender_addr = _parseaddr(sender)
    _LOG.debug(
        'sending message to {} via {}'.format(recipient, sendmail))
    try:
        p = _subprocess.Popen(
            [sendmail, '-F', sender_name, '-f', sender_addr, recipient],
            stdin=_subprocess.PIPE, stdout=_subprocess.PIPE,
            stderr=_subprocess.PIPE)
        stdout,stderr = p.communicate(message_bytes)
        status = p.wait()
        if status:
            raise _error.SendmailError(
                status=status, stdout=stdout, stderr=stderr)
    except Exception as e:

key.replace('-', '_') for key in _config.CONFIG['DEFAULT'].keys()]
    _default_configured_attributes[
        _default_configured_attributes.index('from')
        ] = 'from_email'  # `from` is a Python keyword
    _default_configured_attributes[
        _default_configured_attributes.index('user_agent')
        ] = '_user_agent'  # `user_agent` is a getter that does substitution
    # all attributes that are saved/loaded from .config
    _configured_attributes = (
        _non_default_configured_attributes + _default_configured_attributes)
    # attribute name -> .config option
    _configured_attribute_translations = dict(
        (attr,attr) for attr in _non_default_configured_attributes)
    _configured_attribute_translations.update(dict(
            zip(_default_configured_attributes,
                _config.CONFIG['DEFAULT'].keys())))
    # .config option -> attribute name
    _configured_attribute_inverse_translations = dict(
        (v,k) for k,v in _configured_attribute_translations.items())

    # hints for value conversion
    _boolean_attributes = [
        'digest',
        'force_from',
        'use_publisher_email',
        'active',
        'date_header',
        'trust_guid',
        'trust_link',
        'html_mail',
        'use_css',
        'unicode_snob',