Encode a python long (python 2.x)

def _encode_long(name, value, dummy0, dummy1):
    """Encode a python long (python 2.x)"""
    try:
        return b"\x12" + name + _PACK_LONG(value)
    except struct.error:
        raise OverflowError("BSON can only handle up to 8-byte ints")