Question: Who was the director of the 1964 American musical-fantasy film for which Cotton Warburton is probably best known for editing?

Context paragraphs:
Matt Wayne: Matt S. Wayne is an American writer of comic books and television.  Wayne is probably best known for his work on the animated series "Justice League Unlimited", "" and "The Super Hero Squad Show", and writing and editing comic books for Milestone Media.

Arthur Cotton Moore: Arthur Cotton Moore is an architect in Washington, D.C..  Born in 1935, he grew up in the Kalorama district of Washington, and after attending St. Albans School studied architecture at Princeton University.  He received an Honor Award from the American Institute of Architects in 1977 and became a Fellow of the American Institute of Architects in 1979.  He is known for a style called "industrial baroque" and is probably best known for the Washington Harbour development on the Potomac River in Georgetown, the newer building of The Phillips Collection also in the U.S capital city, and the renovation of the Jefferson Building of the Library of Congress.  He also led the successful restoration of Washington DC's tallest residential building, the Cairo Hotel in 1974.

Mark Moseley (actor): Mark Moseley (born August 2, 1961) is an American voice actor, radio personality and stand-up comedian.  He has appeared in a variety of films, television shows, and video games, and is probably best known as a sound-double for actors such as Eddie Murphy, Patrick Stewart, Arnold Schwarzenegger, Patrick Warburton, and Robin Williams.

Tom Warburton: Thomas Warburton (born August 31, 1968), often credited as Mr. Warburton, is an American animator, producer, writer and designer.  He is best known for creating the animated television series "".  He also created the animated short "Kenny and the Chimp".  Prior to that he served as production designer on the first season of "Beavis and Butt-Head" and was the lead character designer for the animated series "Pepper Ann".  He is also the author of the book "A Thousand Times No".  Since moving to Los Angeles in 2009 he has worked at Disney Television Animation serving as creative director on "Fish Hooks" and co-executive producer on "The 7D".

James Lyons (film editor): James Lyons (October 8, 1960 – April 12, 2007) was an American film editor, screenwriter and actor who frequently collaborated with Todd Haynes.  He is probably best known for editing "The Virgin Suicides" and editing and co-writing "Velvet Goldmine".  He also had a minor role in 1996 film "I Shot Andy Warhol" as Billy Name.

Cotton Warburton: Irvine "Cotton" Eugene Warburton (October 8, 1911 – June 21, 1982) was an American college football quarterback (1933) who became a film and television editor with sixty feature film credits.  He worked for the Metro-Goldwyn-Mayer Studios and for the Walt Disney Studios, and is probably best known for his editing of "Mary Poppins" (1964).

Viva Las Vegas: Viva Las Vegas is a 1964 American musical film starring Elvis Presley and actress Ann-Margret.  Directed by golden age Hollywood musical director George Sidney, the film is regarded by fans and by film critics as one of Presley's best movies, and it is noted for the on-screen chemistry between Presley and Ann-Margret.  It also presents a strong set of ten musical song-and-dance scenes choreographed by David Winters and featured his dancers.  "Viva Las Vegas" was a hit at movie theaters, as it was #14 on the "Variety" year end box office list of the top-grossing movies of 1964.

Roy Radin: Roy Radin (13 November 1949 – 10 June 1983) was a show business promoter who packaged vaudeville shows in the 1970s and early 1980s.  He was probably best known for his attempts to help finance the film "The Cotton Club", and as the subsequent victim of a murder-for-hire at age 33.  The trial in which four people were sentenced related to Radin's killing became known as "The Cotton Club Murder."  The story of Radin's murder became the subject of a book, "Bad Company: Drugs, Hollywood and the Cotton Club Murder".

Mary Poppins (film): Mary Poppins is a 1964 American musical-fantasy film directed by Robert Stevenson and produced by Walt Disney, with songs written and composed by the Sherman Brothers.  The screenplay is by Bill Walsh and Don DaGradi, loosely based on P. L. Travers' book series "Mary Poppins".  The film, which combines live-action and animation, stars Julie Andrews in the role of Mary Poppins who visits a dysfunctional family in London and employs her unique brand of lifestyle to improve the family's dynamic.  Dick Van Dyke, David Tomlinson, and Glynis Johns are featured in supporting roles.  The film was shot entirely at the Walt Disney Studios in Burbank, California using painted London background scenes.

Jeff Kanew: Jeffrey Roger Kanew (born December 16, 1944) is a Jewish American film director, screenwriter, film producer and film editor who early in his career made, with his brother Gary Kanew and director Howard Deutsch, trailers for many films of the 1970s and is probably best known for directing the film "Revenge of the Nerds" (1984) and for editing "Ordinary People".

Supporting paragraphs: Cotton Warburton Mary Poppins (film)
Answer: Robert Stevenson