 Libes's book "Obfuscated C Code and Other Mysteries" explains the winning entries in the Obfuscated C Code Contest, as an educational tool.Libes is best known for Expect, which is public domain software for automating and testing interactive applications such as Telnet, FTP, passwd and hundreds of other programs that have no internal control language (or too limited of a control language) of their own.Libes also developed Expectk, which glues Expect to Tk thereby allowing a character-graphic or line-oriented program to be entirely hidden with a modern graphical user interface.