import base64


def isBase64(sb):
    """
    Check if both string and bytes objects are in base64.
    """

    try:
        if isinstance(sb, str):
            # If there's any unicode here, an exception will be thrown and the function will return false
            sb_bytes = bytes(sb, "ascii")
        elif isinstance(sb, bytes):
            sb_bytes = sb
        else:
            raise ValueError("Argument must be string or bytes")
        return base64.b64encode(base64.b64decode(sb_bytes)) == sb_bytes
    except Exception:
        return False