def METHOD_NAME(self, elements=None, **options) -> str:
    encoded, size = self.boxes_to_b64text(elements, **options)
    decoded = encoded.decode("utf8")
    # see https://tools.ietf.org/html/rfc2397
    return f'<mglyph src="{decoded}" width="{size[0]}px" height="{size[1]}px" />'