A Hawaiian cleaner wrasse provides its cleaning services to a yellowfin goatfish in a reef community off the Big Island in Hawaii. Cleaner species help rid their hosts of ectoparasites, dead tissue, bacteria and fungi. Studies have shown cleaning to play a vital role in keeping many reef ecosystems healthy. (Photo by Marty Snyderman/Caters News Agency)

A young woman holds her smartphone at Red Square with the Kremlin's Spasskaya Tower, right, and St. Basil Cathedral, center, in the background in Moscow, Russia, Monday, July 25, 2016. (Photo by Pavel Golovkin/AP Photo)

A Tamil devotee prays during the Thai Pongal harvest festival at a temple in Colombo January 15, 2016.The Tamil festival of Thai Pongal is a thanksgiving ceremony in which the farmers thank the spirits of nature, the sun and the farm animals for their assistance in providing a successful harvest. (Photo by Dinuka Liyanawatte/Reuters)

A woman peels potatoes for sale at a market located along a railway line in West Jakarta, Indonesia March 1, 2016. (Photo by Garry Lotulung/Reuters)

In this March 29, 2016 photo, a man shoulders a coffin with the remains of a loved one who was slain more than two decades ago by Shining Path rebels, as he walks to the cemetery for a group burial service, in Ccano, a village in the Huanta area of Ayachcuo department, Peru. Presidential candidate Keiko Fujimori's base of support is in places like Ccano, where promises to build roads, clinics and schools recall her agronomist father’s own legacy of delivering aid to the long-overlooked countryside. (Photo by Rodrigo Abd/AP Photo)

This photo taken on March 29, 2017 shows a young woman offering shots of liquer at a dance bar in Walking Street in Pattaya. Two hours east of Bangkok, Pattaya' s bawdy reputation hails from the Vietnam War era when US GIs partied in their downtime. (Photo by Roberto Schmidt/AFP Photo)

Syrian Internal Security Forces dance in celebration during their graduation ceremony, at Ain Issa desert base, in Raqqa province, northeast Syria, Thursday, July 20, 2017. Some 250 residents of Syria's Raqqa province are the latest batch to graduate from a brief U.S-training course that is preparing an internal security force to hold and secure areas as they are captured from Islamic State militants. (Photo by Hussein Malla/AP Photo)

Supporters of the presidential candidate Muhammadu Buhari and his All Progressive Congress hits another supporter with a motorbike during celebrations in Kano, Nigeria March 31, 2015. (Photo by Goran Tomasevic/Reuters)