Formula One - Singapore Grand Prix - Marina Bay, Singapore - 16/9/16 Mercedes' Nico Rosberg of Germany in action during first practice. REUTERS/Jeremy Lee

Formula One - Singapore Grand Prix - Marina Bay, Singapore - 16/9/16 Mercedes' Lewis Hamilton of Britain reviews his second practice. REUTERS/Edgar Su

Oprah Winfrey arrives at the 2015 Vanity Fair Oscar Party in Beverly Hills, California, U.S. on February 22, 2015. REUTERS/Danny Moloshok/File Photo

Republican presidential nominee Donald Trump's campaign plane (R) sits on the same tarmac as Democratic nominee Hillary Clinton's campaign plane (L), at Ronald Reagan Washington National Airport in Washington, U.S., September 16, 2016. REUTERS/Carlos Barria

A supporter of Donald Trump stands in the audience at a campaign rally in Laconia, New Hampshire. REUTERS/Mike Segar

U.S. Democratic presidential candidate Hillary Clinton waves as she boards her campaign plane in Washington, U.S., September 16, 2016. REUTERS/Carlos Barria

Republican presidential nominee Donald Trump delivers remarks at a campaign event at the Trump International Hotel in Washington, D.C., U.S., September 16, 2016. REUTERS/Mike Segar

U.S. Democratic presidential candidate Hillary Clinton speaks at the Black Women's Agenda Annual Symposium in Washington, U.S., September 16, 2016. REUTERS/Carlos Barria