A woman mourns the loss of her husband, next to a placard which reads “I'm a pusher”, who was shot dead by an unidentified gunman in Manila on July 23, 2016. Philippine President Rodrigo Duterte swept to power in May on a promise to clampdown on drugs, and police have since confirmed killing nearly 200 people in a two-month crime blitz. There has also been a surge in killings by anti-drug vigilantes who leave victims' corpses on city streets wrapped in packaging tape with signs accusing them of being drug dealers. (Photo by Noel Celis/AFP Photo)

A hot air balloon in the shape of children's comic Rupert Bear is seen tethered before a tethered flight at the Bristol International Balloon fiesta in south west England, Britain, August 10, 2018. (Photo by Adrian Sherratt/The Guardian)

Medieval jousters Luke Binks (L) and Andrew McKinnon pose for a photograph in Sydney, Australia, August 16, 2017 during a photo call for the World Jousting Championships to take place in Sydney on September 23 and 24. (Photo by Dan Himbrechts/Reuters/AAP)

A man performs a split as he practices Kung Fu at Beihai Park in Beijing, China August 20, 2017. (Photo by Reuters/China Stringer Network)

Kendall Jenner and Kylie Jenner seen in this celebrity social media picture on September 1, 2016. (Photo by XposurePhotos.com)

A police officer wearing a protective mask walks past the portrait of late communist leader Mao Zedong (not pictured) at Tiananmen Gate in Beijing on January 23, 2020. Large-scale Lunar New Year events in Beijing have been cancelled as part of national efforts to control the spread of a new SARS-like virus, city authorities announced on January 23. (Photo by Nicolas Asfouri/AFP Photo)

A dead crocodile is seen on Huangsha Seafood Market in Guangzhou, Guandong Province, China, 22 January 2018. Tsukiji Market of China or Huangsha Seafood Market is biggest one in Southern China and one of the biggest in China, as there are literally hundreds of different varieties of fish and seafood scattered throughout the market. (Photo by Aleksandar Plavevski/EPA/EFE)

A handout photograph provided by Brian Kubicki of Costa Rican Amphibian Research Center on 26 April 2016 shows a “Crystal frog”, Hyalinobatrachium dianae (H. diane). This frog was discovered by US biologist Brian Kubicki and Costa Ricans Stanley Salazar and Robert Puschendorf in a rainy forest of Costa Rican caribbean after 40 years without notice of any new example of this kind. (Photo by Brian Kubicki/EPA/Costa Rican Amphibian Research Center)