Black-headed gulls sit on pickets at a riverside in Tokyo, Japan, December 27, 2015. (Photo by Toru Hanai/Reuters)

Medic James E. Callahan of Pittsfield, Mass., gives mouth-to-mouth resuscitation to a dying soldier in war zone D, about 50 miles northeast of Saigon, June 17, 1967. Thirty-one men of the 1st Infantry Division were reported killed in the guerrilla ambush, with more than 100 wounded. (Photo by Henri Huet/AP Photo)

A couple takes a selfie as Hoa Binh hydroelectric power plant opens the flood gates after a heavy rainfall caused by Talas typhoon in Hoa Binh province, outside Hanoi, Vietnam July 20, 2017. (Photo by Reuters/Kham)

A hippopotamus performs during a show at the circus in Krasnoyarsk, Siberia, Russia, July 7, 2016. (Photo by Ilya Naymushin/Reuters)

A woman carries a floral design handbag at the RHS Chelsea Flower Show in London, Britain on May 21, 2018. The annual show of floral art, timed to coincide with the RHS Chelsea Flower Show nearby, sees over sixty shops, restaurants and local businesses compete for prizes, with the awards given by RHS (Royal Horticultural Society) judges, this year on the theme of “Summer of Love”. (Photo by Toby Melville/Reuters)

Projectionist Antonio Feliciano, 75, checks his projector before showing a film in Monforte, Portugal May 16, 2015. Shades of Oscar-winning classic "Cinema Paradiso" run through the life of Feliciano, a sprightly 75-year-old who fears he may be the last of Portugal's travelling film projectionists.After six decades travelling four million km (2.5 million miles) to screen 4,000 films in Portugal's far-flung villages, Feliciano does not plan to retire just yet. But he is resigned to the fact that the Internet, digital TV and distribution monopolies have made his craft obsolete. (Photo by Rafael Marchante/Reuters)

Armed police Taser a man inside the grounds of the Houses of Parliament on 11 December 2018. (Photo by Peter Nicholls/Reuters)

A Saudi soldier fires a mortar towards Houthi movement position, at the Saudi border with Yemen April 21, 2015. (Photo by Reuters/Stringer)