A fox walks past 10 Downing Street in London, Britain January 16, 2018. REUTERS/Hannah McKay

People cast long shadows in the winter sunlight as they walk across a plaza in the Canary Wharf financial district of London, Britain, January 17, 2018. REUTERS/Dylan Martinez

View of a bridge under construction that collapsed leaving dead and injured workers in Chirajara near Bogota, Colombia January 15, 2018. REUTERS/Jaime Saldarriaga

A Rohingya refugee boy plays with a glove balloon at a Samaritan's Purse diphtheria clinic at Balukhali camp, near Cox's Bazar, Bangladesh January 15, 2018. REUTERS/Tyrone Siu

Devotees offer prayers before taking a holy bath in the Bagmati River at Pashupatinath Temple during the Swasthani Brata Katha festival in Kathmandu, Nepal, January 16, 2018. REUTERS/Navesh Chitrakar

A nurse checks a premature baby in an incubator at the child care unit of a hospital in Sanaa, Yemen January 16, 2018. REUTERS/Khaled Abdullah

A murmuration of migrating starlings is seen across the sky near the village of Beit Kama in southern Israel January 16, 2018. REUTERS/Amir Cohen

Tennis - Australian Open - Rod Laver Arena, Melbourne, Australia, January 18, 2018. Gael Monfils of France serves against Novak Djokovic of Serbia. REUTERS/David Gray

Rescue workers scour through cars for missing persons after a mudslide in Montecito, California, U.S. January 12, 2018. REUTERS/Kyle Grillot

Pope Francis boards for his trip to Chile and Peru at Fiumicino International Airport in Rome, Italy, January 15, 2018. REUTERS/Max Rossi

A man rides a horse through flames during the annual "Luminarias" celebration on the eve of Saint Anthony's day, Spain's patron saint of animals, in the village of San Bartolome de Pinares, northwest of Madrid, Spain, January 16, 2018. Picture taken January 16, 2018. REUTERS/Juan Medina

A person enters a sauna on the peak of Mount Lagazuoi in Cortina D'Ampezzo, Italy January 16, 2018. Picture taken January 16, 2018. REUTERS/Stefano Rellandini

Protesters clash with riot police during a demonstration outside the parliament building against planned government reforms in Athens, Greece January 12, 2018. REUTERS/Alkis Konstantinidis

Palestinian children play at their family's house in Al-Shati refugee camp in Gaza City January 15, 2018. REUTERS/Mohammed Salem

U.S. President Donald Trump confers with White House Communications Director Hope Hicks (L) as White House Press Secretary Sarah Sanders (R) listens during an interview with Reuters at the White House in Washington, U.S., January 17, 2018. REUTERS/Kevin Lamarque