A Femen activist, Sarah Constantin, is hanged from a noose-like rope from a Paris bridge to call attention to the large number of executions in Iran as she stages a protest against visiting Iranian President Hassan Rouhani in Paris, Thursday, January 28, 2016. A near-naked woman hanging from a noose-like rope from a Paris bridge has sent a message to visiting Iranian President Hassan Rouhani. (Photo by Zacharie Scheurer/AP Photo)

A Sri Lankan leopard is pictured at a zoo in Dehiwala near Colombo on March 3, 2016, on World Wildlife Day. (Photo by Ishara S. Kodikara/AFP Photo)

Runner English Gardner poses for a portrait at the U.S. Olympic Committee Media Summit in Beverly Hills, Los Angeles, California March 8, 2016. “My musical inspiration when I'm training is usually a lot of upbeat music”, said Gardner. (Photo by Lucy Nicholson/Reuters)

Bjorn, aged 5, smiles as he poses with a Owl butterfly during an event to launch the Sensational Butterflies exhibition at the Natural History Museum in London, Britain March 23, 2016. The exhibition opens to the public on March 24 and runs until September 11. (Photo by Dylan Martinez/Reuters)

In this Saturday, July 4, 2015 photo, Israeli and Russian members of knight clubs cook their breakfast before the reenactment of the Battle of Hattin in Lavi Forest, northern Israel. About a third of the participants arrived with their elaborate gear from Russia. The project is supported by the Lower Galilee Regional Council. (Photo by Oded Balilty/AP Photo)

An Armatix employee holds a “smart gun” by the company at the Armatix headquarters in Munich May 14, 2014. The gun is implanted with an electronic chip that allows it to be fired only if the shooter is wearing a watch that communicates with it through a radio signal. If the gun is moved more than 10 inches (25 cm) from the watch, it will not fire. A Maryland gun shop owner has dropped his plan to be the first in the United States to sell the so-called “smart gun” after a backlash that included death threats. (Photo by Michael Dalder/Reuters)

This picture taken on July 15, 2014 shows a bridge submerged in floodwaters in the ancient town of Fenghuang, central China's Hunan province. Rainstorms lashed central China's Hunan Province and southwest China's Guizhou Province, affecting over 1 million people and flooding a historical town, state media reported. (Photo by AFP Photo)

A young man weaves palm fronds into the shape of a cross before the start of a Mass to observe Palm Sunday, at the Metropolitan Cathedral, in Managua, Nicaragua, Sunday, March 29, 2015. For Christians, Palm Sunday marks the start of Holy Week ahead of Easter, commemorating Jesus Christ's entrance into Jerusalem, when his followers laid palm branches in his path. (Photo by Esteban Felix/AP Photo)