def cards(title, text, card_type='Simple', image=None):
    """
    Returns alexa cards

    :param str title: A string containing the title of the card.
    :param str text: A string containing the text content for a Standard card
        (not applicable for cards of type Simple)
    :param str card_type: A string describing the type of card to render. Valid types are:
        * "Simple": A card that contains a title and plain text content.
        * "Standard": A card that contains a title, text content, and an image to display.
    :param dict image: An image object that specifies the URLs for the image to display on a Standard card.
        Only applicable for Standard cards.
        You can provide two URLs, for use on different sized screens.
        * smallImageUrl
        * largeImageUrl
    :return: Dictionary with cards details
    :rtype: dict

    Alexa API Reference:
        https://developer.amazon.com/docs/custom-skills/request-and-response-json-reference.html#card-object

    """
    cards = {'type': card_type, 'title': title}
    if card_type == 'Standard':
        cards['text'] = text
    else:
        cards['content'] = text
    if image:
        cards['image'] = image
    return cards
