def fatal(message, **kwargs):
    error(message, level="fatal", **kwargs)
def image_url(self, pixel_size=None):
        """
        Get the URL for the user icon in the desired pixel size, if it exists. If no
        size is supplied, give the URL for the full-size image.
        """
        if "profile" not in self._raw:
            return
        profile = self._raw["profile"]
        if (pixel_size):
            img_key = "image_%s" % pixel_size
            if img_key in profile:
                return profile[img_key]
        return profile[self._DEFAULT_IMAGE_KEY]