New York Police Department tactical police officers stand guard near the New York Stock Exchange on September 9, 2011 in New York City. Officials are stepping up security in New York and Washington D.C. a day after U.S. officials received a credible but unconfirmed terror threat to utilize car bombs on bridges or tunnels in New York or Washington. (Photo by Justin Sullivan/Getty Images)

Models backstage at the Lagos Fashion & Design Week in Nigeria on October 26, 2016. The opening night attracted models, buyers, consumers and the media to view the latest creations by African designers, five of whom were showcasing plus-size collections in the Nigerian city. (Photo by Stefan Heunis/AFP Photo)

Dogs, Pretty, Llilly, and Rocky wait for their turn to be examined by veterinarians during a community campaign for the sterilisation and deworming of dogs and cats in Havana, Cuba February 25, 2016. (Photo by Reuters/Stringer)

Beauty contestants prepare backstage before the fashion show of Miss Tiffany's Universe 2016 transvestite contest in Bangkok, Thailand, April 20, 2016. (Photo by Athit Perawongmetha/Reuters)

Protestors disperse color paint during a protest against the government, at central square, during an anti-government protest in Skopje on June 6, 2016, in a series of protests dubbed Colourful Revolution. Macedonia's president on June 6, 2016 said he was revoking all the controversial pardons he had granted in April to dozens of people implicated in a huge wiretapping scandal. President Gjorge Ivanov had on April 12 said he was halting probes into 56 Macedonians suspected of involvement in the scandal – a surprise decision that sparked international condemnation and angry street protests. (Photo by Robert Atanasovski/AFP Photo)

Fifth Harmony accept the most buzzworthy international artist or group award during the iHeartRadio Much Music Video Awards (MMVAs) in Toronto, Ontario, Canada June 19, 2016. (Photo by Fred Thornhill/Reuters)

The Photographers 2015 runs from 25 November to 23 December at Osborne Samuel and Beetles+Huxley, London. Here: Untitled, 1950, by Bert Hardy. (Photo by Bert Hardy/Beetles+Huxley & Osborne Samuel)

People gather at the site of a bomb explosion in Sanaa December 23, 2014. Five bombs exploded on Tuesday in Sanaa's old quarter, where many supporters of the Shi'ite Muslim Houthi group live, killing at least one person and wounding another, a Yemeni security official said. No one has claimed responsibility for the attacks, but the Houthis have been fighting the Sunni Islamist militant al Qaeda group and allied tribesmen since its gunmen captured Sanaa in September and forced the resignation of a government they had long seen as corrupt. (Photo by Khaled Abdullah/Reuters)