While musical genius Stephen Sondheim has generally written both words and music for his productions, two of his best-known musicals, written at the beginning of his career, contain only his lyrics.The famed composer Leonard Bernstein wrote the music for “West Side Story,” and Jules Styne, one of Broadway’s and Hollywood’s most prolific songwriters, wrote the score for “Gypsy.” “Gypsy,” the sensational 1959 hit, with book by …