def get_img_url(img_src, url_base):
    """
    Get an image url from the src attribute af an image, and the page base url
    """
    if not img_src:
        return None
    if not "//" in img_src: ## it's not an absolute url
        if img_src[0] == "/":
            img_src = img_src[1:]
        img_src = url_base + img_src
    return img_src