sorting/mem_transformer.py import Error

[cosmoquester]

import torch
import torch.nn as nn
import torch.nn.functional as F
from attention import ContinuousAttention
from long_term_attention import LongTermAttention 
from long_term_attention_transformer import LongTermAttentionTransformer

This is the content of sorting/mem_transformer.py, but there is no attention.py or long_term_attention_transformer.py
so there are import error on doing sorting task with direction in the README.md