A tractor trailer drives through flash flood waters that overran Skunk Creek, Tuesday, August 19, 2014, in northwestern Phoenix. Flooding from heavy rain in the Phoenix area has forced authorities to close several major roads, including a portion of Interstate 17 about 25 miles north of the city. (Photo by Matt York/AP Photo)

A partially burned American flag lies on the street near the spot where Michael Brown was killed before an event to mark the one year anniversary of his killing in Ferguson, Missouri August 9, 2015. (Photo by Rick Wilking/Reuters)

People wait on a taxi line near Madison Square Garden, Wednesday, September 23, 2015, as a 225-foot-tall hand-painted billboard of Pope Francis stands out at Eighth Avenue in New York. The billboard, designed by Israel Ochoa of DeSales Media, including a photo by photographer Giulio Napolitano, marks the arrival of the pope Thursday. (Photo by Craig Ruttle/AP Photo)

A visitor stands in front of a portrait taken by artist Bruce Gilden at the “Masters of Photography” exhibition at the Photokina trade fair in Cologne on September 20, 2016. The fair for the photographic and imaging sector, that is running from September 20 to 25, 2016, presents products from image capture, image processing and storage to image output. Photokina also includes a program of events with congresses, workshops, symposiums and photography exhibitions. (Photo by Patrik Stollarz/AFP Photo)

Crowds look on as the super moon rises behind the Fremantle War Memorial at Monument Hill on November 14, 2016 in Fremantle, Australia. A super moon occurs when a full moon passes closes to earth than usual, with the November 14th moon expected to be closer than it has been in over 70 years. (Photo by Paul Kane/Getty Images)

Humanoid robots compete in a group match of the 20th RoboCup in Leipzig, Germany, June 30, 2016. About 3,500 participants from 45 countries and regions compete in the robot world championship until 04 July. (Photo by Sebastian Willnow/EPA)

A man protesting the Ferguson grand jury decision to not indict officer Darren Wilson in the Michael Brown case is arrested while marching through the streets on December 1, 2014 in New York City. Brown, an 18-year-old black man, was killed by Darren Wilson, a white Ferguson, MO police officer, on August 9. (Photo by Andrew Burton/Getty Images)

A vintage military aircraft is seen parked ahead of the International Air and Space Fair (FIDAE) at the Arturo Merino Benitez international airport in Santiago, Chile March 29, 2016. (Photo by Rodrigo Garrido/Reuters)