Question: Who is an American composer who wrote "Could I leave you?"

full_context: Document 1: Sally (musical): Sally is a musical comedy with music by Jerome Kern, lyrics by Clifford Grey and book by Guy Bolton (inspired by the 19th century show, "Sally in our Alley"), with additional lyrics by Buddy De Sylva, Anne Caldwell and P. G. Wodehouse. The plot hinges on a mistaken-identity: Sally, a waif, is a dishwasher at the Alley Inn. She poses as a famous foreign ballerina and rises to fame (and finds love) through joining the Ziegfeld Follies. There is a rags to riches story, a ballet as a centrepiece, and a wedding as a finale. "Look for the Silver Lining" continues to be one of Kern's most familiar songs. The song is lampooned by another song, "Look for a Sky of Blue," in Rick Besoyan's satirical 1959 musical "Little Mary Sunshine".
Document 2: Finishing the Hat: Finishing the Hat: Collected Lyrics (1954–1981) with Attendant Comments, Principles, Heresies, Grudges, Whines and Anecdotes is a book by American musical theatre composer and lyricist Stephen Sondheim. The book contains Sondheim's lyrics from his first professionally staged show, "Saturday Night" (1954) through "West Side Story", "", "A Funny Thing Happened on the Way to the Forum", "Anyone Can Whistle", "Do I Hear a Waltz?", "Company", "Follies", "A Little Night Music", "The Frogs", "Pacific Overtures", "", and ending with "Merrily We Roll Along" (1981), stopping just short of the Pulitzer Prize-winning "Sunday in the Park with George" (1984) which contains the song from which the title of the book is taken.
Document 3: She's Leaving Home: "She's Leaving Home" is a Lennon–McCartney song, released in 1967 on the Beatles album "Sgt. Pepper's Lonely Hearts Club Band". Paul McCartney wrote and sang the verse and John Lennon wrote the chorus, which they sang together. Neither George Harrison nor Ringo Starr was involved in the recording. The song's instrumental background was performed entirely by a small string orchestra arranged by Mike Leander, and was one of only a handful of Beatles songs in which the members did not play any instruments on the recording.
Document 4: Sheldon Harnick: Sheldon Harnick (born April 30, 1924) is an American lyricist best known for his collaborations with composer Jerry Bock on musicals such as "Fiddler on the Roof".
Document 5: Could I Leave You? (song): "Could I Leave You?" is a song written by Stephen Sondheim for the 1971 musical "Follies" for the character Phyllis.
Document 6: Passion (musical): Passion is a one-act musical, with music and lyrics by Stephen Sondheim and a book by James Lapine. The story was adapted from Ettore Scola's film "Passione d'Amore", itself adapted from the novel "Fosca" by Iginio Ugo Tarchetti. Central themes include love, sex, obsession, illness, passion, beauty, power and manipulation. "Passion" is notable for being one of the few projects that Stephen Sondheim himself conceived, along with "Sweeney Todd" and "Road Show".
Document 7: Stephen Flaherty: Stephen Flaherty (born September 18, 1960) is an American composer of musical theatre. He works most often in collaboration with the lyricist/bookwriter Lynn Ahrens. They are best known for writing the Broadway musicals "Once on This Island", which was nominated for eight Tony Awards, "Seussical", which was nominated for the Grammy Award, and "Ragtime", which was nominated for twelve Tony Awards and won Best Original Score. Flaherty was also nominated for two Academy Awards and two Golden Globe Awards with Lynn Ahrens for his songs and song score for the animated film musical "Anastasia".
Document 8: The Sondheim Review: The Sondheim Review is a quarterly magazine published in Chicago, United States, since 1994 and, per its tagline, is "Dedicated to the work of the Musical Theatre's foremost composer and lyricist," Stephen Sondheim. It is edited by Cincinnati theatre critic Rick Pender, and its editorial board includes theatre columnist John Olson and drama critic Eric Grode. Sondheim himself has written occasional short items for the magazine, although he is not formally connected with the magazine in any way.
Document 9: If My Friends Could See Me Now: "If My Friends Could See Me Now", with music by Cy Coleman and lyrics by Dorothy Fields, is a song from the 1966 Broadway musical "Sweet Charity". In the musical the character of Charity, played in the original New York cast by Gwen Verdon, reflects on her marvellous luck as she spends time with Vittorio. In the 1969 film adaptation of "Sweet Charity", "If My Friends Could See Me Now" is performed by Shirley MacLaine.
Document 10: Sweeney Todd: The Demon Barber of Fleet Street: Sweeney Todd: The Demon Barber of Fleet Street is a 1979 musical thriller with music and lyrics by Stephen Sondheim and book by Hugh Wheeler. The musical is based on the 1973 play "Sweeney Todd, the Demon Barber of Fleet Street" by Christopher Bond.
Document 11: Send In the Clowns: "Send in the Clowns" is a song written by Stephen Sondheim for the 1973 musical "A Little Night Music", an adaptation of Ingmar Bergman's film "Smiles of a Summer Night". It is a ballad from Act Two, in which the character Desirée reflects on the ironies and disappointments of her life. Among other things, she looks back on an affair years earlier with the lawyer Fredrik. Meeting him after so long, she finds that he is now in an unconsummated marriage with a much younger woman. Desirée proposes marriage to rescue him from this situation, but he declines, citing his dedication to his bride. Reacting to his rejection, Desirée sings this song. The song is later reprised as a coda after Fredrik's young wife runs away with his son, and Fredrik is finally free to accept Desirée's offer.
Document 12: Stephen Sondheim: Stephen Joshua Sondheim ( ; born March 22, 1930) is an American composer and lyricist known for more than a half-century of contributions to musical theatre. Sondheim has received an Academy Award, eight Tony Awards (more than any other composer, including a Special Tony Award for Lifetime Achievement in the Theatre), eight Grammy Awards, a Pulitzer Prize, a Laurence Olivier Award, and a 2015 Presidential Medal of Freedom. He has been described by Frank Rich of "The New York Times" as "now the greatest and perhaps best-known artist in the American musical theater." His best-known works as composer and lyricist include "A Funny Thing Happened on the Way to the Forum", "Company", "Follies", "A Little Night Music", "Pacific Overtures", "", "Merrily We Roll Along", "Sunday in the Park with George", "Into the Woods", "Assassins", and "Passion". He also wrote the lyrics for "West Side Story" and "Gypsy".
Document 13: West Side Story: West Side Story is a musical with a book by Arthur Laurents, music by Leonard Bernstein, lyrics by Stephen Sondheim and conception and choreography by Jerome Robbins. It was inspired by William Shakespeare's play "Romeo and Juliet".
Document 14: Jonathan Tunick: Jonathan Tunick (born April 19, 1938, New York City) is an American orchestrator, musical director, and composer, one of twelve people to have won all four major American show business awards: the Tony Awards, Academy Awards, Emmy Awards and Grammy Awards. He is best known for his work with Stephen Sondheim, starting in 1970 with "Company" and continuing to the present day.
Document 15: Oscar Hammerstein II: Oscar Greeley Clendenning Hammerstein II ( ; July 12, 1895 – August 23, 1960) was an American librettist, theatrical producer, and (usually uncredited) theatre director of musicals for almost forty years. Hammerstein won eight Tony Awards and two Academy Awards for Best Original Song. Many of his songs are standard repertoire for vocalist's and jazz musicians. He co-wrote 850 songs. Hammerstein was the lyricist and playwright in his partnerships; his collaborators wrote the music. Hammerstein collaborated with numerous composers, such as Jerome Kern, with whom he wrote "Show Boat", Vincent Youmans, Rudolf Friml, Richard A. Whiting and Sigmund Romberg; but he is best known for his collaborations with Richard Rodgers, as the duo Rodgers and Hammerstein which include "Oklahoma!", "Carousel", "South Pacific", "The King and I", and "The Sound of Music".
ground_truth: Stephen Sondheim