def METHOD_NAME(string, content_type="application/octet-stream"):
    """Returns JSON-safe version of `string`.
    If `string` is a Unicode string or a valid UTF-8, it is returned unmodified,
    as it can safely be encoded to JSON string.
    If `string` contains raw/binary data, it is Base64-encoded, formatted and
    returned according to "data" URL scheme (RFC2397). Since JSON is not
    suitable for binary data, some additional encoding was necessary; "data"
    URL scheme was chosen for its simplicity.
    """
    try:
        string = string.decode("utf-8")
        json.dumps(string)
        return string
    except (ValueError, TypeError):
        return b"".join([b"data:", content_type.encode("utf-8"), b";base64,", base64.b64encode(string)]).decode("utf-8")