Introduce back-to-back word lines

Hui pattern is called Hui pattern because it is shaped like Hui in Chinese characters. If you pay attention in your life, you will find that there are many palindromes around you: positive and negative palindromes on fabrics, single palindromes on porcelain, and even a new mobile phone keyboard from Nokia all adopt zigzag design, and palindromes are used in classical furniture countless times. As a traditional decorative pattern, palindrome has experienced hundreds and thousands of years of evolution and is still deeply loved by people.