American composer and lyricist Stephen Sondheim has released a book Finishing the Hat: The Collected Lyrics of Stephen Sondheim, with Attendant Comments, Principles, Heresies, Grudges, Whines and Anecdotes.  The following is an extract from interview an article on Sondheim by Emma Brockes: Initially a maths student at Williams College in Massachusetts, the young Sondheim took…