In this exercise we consider a fairly primitive form of encryption. Open the file perl_regexps.txt¹ using the text editor vi. Next, enter the following substitution commands in the exact order given

1. 1,$s/\(.\)\1/&&/g

2. 1,$s/\(.\)\(.\)\2\2\2/\2\2\2\1\2/g

3. 1,$s/\(.\)\(.\)\(.\)\(.\)/\3\1\4\2/g

4. 1,$s/\(...\)\(...\)/\2\1/g

in order to make the file unreadable. What four substition commands should be given next in order to restore the file in its original state?