Question: What is the nationality of the director of a film that premiered at the Sundance Film Festival?
Context: Jordan Charles Vogt-Roberts (born September 22, 1984) is an American film and television director and screenwriter.  His feature directorial debut, "The Kings of Summer", screened at the 2013 Sundance Film Festival, where it was nominated for the Grand Jury Prize, and also at the 2013 Cleveland International Film Festival.  The film won the Narrative Feature Audience Award at the 2013 Dallas International Film Festival.  He also wrote and directed a short film which screened at the Sundance Film Festival and SXSW, "Successful Alcoholics".  He also co-wrote and directed the TV series "Mash Up".  In 2017, Vogt-Roberts directed the MonsterVerse film "". Giona Ostinelli (born March 12, 1986) is a Swiss–Italian composer who resides and works in Los Angeles.  He has written scores for over 30 feature films that premiered at Sundance Film Festival, Tribeca Film Festival, Cannes International Film Festival, South by Southwest Film Festival, Fantastic Fest, FrightFest, Cincinnati Film Festival, Hamptons International Film Festival, Palm Springs International Film Festival, Fort Lauderdale International Film Festival, Chicago International Children's Film Festival, among others.  Ostinelli's score for breakout psychological thriller "Darling" released by Lakeshore Records and fan favorite Mondo Records has been described as "one of the most interesting and innovative soundscapes...".  His soundtrack for "POD" has been shortlisted for the Academy Awards for Best Original Score. Heidi Ewing is a director, producer, and writer of documentary films.  She and Rachel Grady founded Loki Films in 2001, and have collaborated on several documentaries together.  She is best known as the co-director of "Jesus Camp", which was nominated for an Academy Award for best documentary in 2006.  Next came"12th & Delaware" (HBO), which premiered at the 2010 Sundance Film Festival.  The film "casts a heart-rending light on the abortion divide" (LA Times) and was honored with a Peabody Award.  "Detropia", a poetic look at Ewing's home town, also won several awards, including Best Editing at Sundance 2012, Outstanding Direction and Outstanding Original Score, at the 2013 Cinema Eye Honors for Nonfiction Filmmaking and a News and Documentary Emmy for editing.  "Norman Lear: Just Another Version of You" was the opening night selection of the 2016 Sundance Film Festival and premiered on PBS American Masters on October 25, 2016.  Other films as a director include "The Boys of Baraka", "Freakonomics", and "The Education of Mohammed Hussein". Dee Rees is an American screenwriter and director best known for her feature films "Pariah", "Bessie" and "Mudbound". Jim Hosking is a British film director.  His first short film, "Little Clumps Of Hair", premiered on BBC3.  His short film "Renegades" premiered at the Sundance Film Festival in 2010.  He directed the segment "G is for Grandad" for the film "ABCs of Death 2" in 2014.  His first feature film "The Greasy Strangler" premiered at the Sundance Film Festival on 22 January 2016. Patrick Creadon (born May 1, 1967) is an American film director primarily known for his work in independent documentary films.  His first film, "Wordplay", profiled "New York Times" crossword editor Will Shortz and premiered at the 2006 Sundance Film Festival.  Soon after its premiere, "Wordplay" became the second-highest grossing documentary of that year.  His second film, "I.O.U.S.A.", examined America's debt problem and forecast the global financial crisis of 2008-2009.  "I.O.U.S.A" premiered at the 2008 Sundance Film Festival and was later named one of film critic Roger Ebert's Top 5 Documentaries of the Year. Jennifer Phang is a filmmaker most known for her feature films "Advantageous" (2015), which premiered at the 2015 Sundance Film Festival and won a Special Jury Award for Collaborative Vision there and was also based on her award-winning short film of the same name, and "Half-Life" (2008), which also premiered at the 2008 Sundance Film Festival and won "Best Film" awards at a number of film festivals including the Gen Art Film Festival, the San Francisco International Asian American Film Festival (now known as CAAMFest) as well an "Emerging Director Award" at the Asian American International Film Festival. Peter Richardson is an American documentary film director.  A native of Philomath, Oregon, Richardson is a 1998 graduate of Philomath High School and attended University of Notre Dame on a scholarship.  After graduating from Notre Dame with a Bachelor of Arts degree in Film Production & Theory, Richardson moved to Los Angeles where he worked for a short time at a publicity company before moving back to Oregon to start work on his first film.  Richardson has directed two award-winning feature documentaries.  His first film, "" debuted at the 2006 Sundance Film Festival.  The film was later aired on the Sundance Channel.  Richardson's second film, "How to Die in Oregon", premiered on January 23 at the 2011 Sundance Film Festival.  In addition to directing the film, Richardson also acted as cinematographer, editor, and producer on "How to Die in Oregon".  The critically acclaimed film went on to win the Grand Jury Prize in the US Documentary competition.  The film premiered on HBO on May 26, 2011.  Richardson was the cinematographer on Irene Taylor Brodsky's documentary short film, "Saving Pelican 895", which aired on HBO on April 20, 2011. Mudbound is a 2017 period drama film directed by Dee Rees, with a script written by Virgil Williams based on the novel "Mudbound" by Hillary Jordan.  It stars Carey Mulligan, Garrett Hedlund, Jason Clarke, Jason Mitchell and Mary J. Blige.  It premiered at the 2017 Sundance Film Festival on January 21, 2017.  It premieres on Netflix and in theaters on November 17, 2017. The Sundance Film Festival, a program of the Sundance Institute, is a film festival that takes place annually in Park City, Utah.  With over 46,660 attendees in 2016, it is the largest independent film festival in the United States.  Held in January in Park City and Salt Lake City, Utah, as well as at the Sundance Resort, the festival is a showcase for new work from American and international independent filmmakers.  The festival comprises competitive sections for American and international dramatic and documentary films, both feature films and short films, and a group of out-of-competition sections, including NEXT, New Frontier, Spotlight, Midnight, Premieres and Documentary Premieres.  The 2017 Sundance Film Festival took place from January 19 to January 29, 2017.
Answer: American