A giant panda cub is pictured in an incubator at the Ya'an Bifengxia Giant Panda Breeding and Research Center in Ya'an city, southwest China's Sichuan province, 21 August 2015. Ten tiny panda cubs made their first public appearance at China's Ya'an Bifengxia Giant Panda Breeding and Research Center in southwestern Sichuan province on Friday (21 August 2015). All of the ten giant pandas were born in 2015. The oldest of them is just two month old, while the youngest one was born a week ago. This marks the first time they were put together as a group since they were born. (Photo by Imaginechina/Splash News)

“The Challenge!” Young boy relishes in a game of tug of war before school. Photo location: Lake Titicaca, Peru. (Photo and caption by Paul Heyman/National Geographic Photo Contest)

A Syrian boy looks through a gate as others wait to cross into Syria at Oncupinar border crossing in the southeastern city of Kilis, Turkey February 11, 2016.. (Photo by Osman Orsal/Reuters)

David Goffin of Belgium meets a koala during a promotional event for the Australian Open tennis tournament at Melbourne Park on January 17, 2018. (Photo by Fiona Hamilton/Reuters/Tennis Australia)

A Southwest Airlines jet takes off from Reagan National Airport with a thunderhead to the east on June 20, 2017 in Alexandria, VA. (Photo by Jonathan Newton/The Washington Post)

Maria Menounos and Derek Hough sit courtside as the Celtics play the Lakers in Los Angeles, March 2012. (Photo by Lucy Nicholson/Reuters)

Women wearing bikinis and Santa Claus hats participate in a promotional event to celebrate the upcoming Christmas at a ski resort in Xuchang, Henan province, December 23, 2014. Ten women wore Santa Claus-themed bikinis to welcome the coming Christmas in temperatures below zero Celsius. (Photo by Reuters/Stringer)