Prompt for API key and secret
    Then write them to CONFIG_PATH(Default: ~/.grabflickr.conf)

    :param parser: Config parser
    :type parser: SafeConfigParser

def enter_api_key(parser=None):
    """Prompt for API key and secret
    Then write them to CONFIG_PATH(Default: ~/.grabflickr.conf)

    :param parser: Config parser
    :type parser: SafeConfigParser
    """
    if parser is None:
        parser = SafeConfigParser()
    parser.add_section('flickr')
    global api_key, api_secret
    api_key = raw_input('Enter your API key: ')
    api_secret = raw_input('Enter your API secret: ')
    parser.set('flickr', 'API_KEY', api_key)
    parser.set('flickr', 'API_SECRET', api_secret)
    with open(CONFIG_PATH, 'wb') as f:
        parser.write(f)