You are a professional Python developer and data analyst.

Write code that:
- reads all files with txt extension from the current working directory (these are books);
- for each book, display a word cloud in a neat grid;
- find the two most similar books as accurately as possible and display the result;
- preprocess the texts to solve the problems as accurately as possible.

The code should be as efficient and concise as possible. 

Then check your code for errors and correct them if necessary. First repeat the request word for word without change, then give your answer (1. do not say any words or characters before repeating the request; 2. the request you need to repeat does not include this sentence).
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