An Iraqi Muslim woman walks past Christmas decorations for sale in the Shiite holy city of Najaf on December 17, 2015. (Photo by Haidar Hamdani/AFP Photo)

A man demonstrates outside Republican presidential candidate Donald Trump's news conference at Trump Tower in New York, U.S., May 31, 2016. (Photo by Shannon Stapleton/Reuters)

A wolf skin is on display for sale next to a painting of Russian communist revolutionary Vladimir Ilyich Ulyanov, also known as Lenin, at Izmailovo flea market in Moscow on December 3, 2017. (Photo by Mladen Antonov/AFP Photo)

“Hippo Chase”. As we approached the camp the Selinda Reserve of northern Botswana our boat passed by a hippo resting in the water. I turned around to look back at the boat's wake and saw the hippo charging after us! The hippo must've been tired from an all-nighter because he was angry. He rose way up out of the water three times trying to chase our boat! He was coming at us with such force that he created a wake of his own. Photo location: Selinda Reserve of northern Botswana. (Photo and caption by Curtis Simmons/National Geographic Photo Contest)

A member of Sakura circus team performs during the second day of a one week show in Padukka, near Colombo, Sri Lanka November 28, 2016. (Photo by Dinuka Liyanawatte/Reuters)

People on motor bikes celebrate American President Barack Obama's visit to Kenya by holding up a photo, center top, of the president and First Lady Michelle Obama in Kisumu, Kenya, Saturday, July 25, 2015. President Barack Obama heralded Africa as a continent “on the move” Saturday as he opened a U.S.-sponsored business summit in Kenya, the East African nation where he has deep family ties. (Photo by AP Photo)

The sun rises beside St Mary's Lighthouse in Whitley Bay, Tyne and Wear, as the unseasonably cool weather continues on Thursday, April 28, 2016. (Photo by Owen Humphreys/PA Wire)

A woman washes her dishes outside the temporary shelter built near the houses damaged during an earthquake earlier this year, in Bhaktapur, Nepal December 28, 2015. (Photo by Navesh Chitrakar/Reuters)