Attendees dressed as Poison Ivy and Harley Quinn arrive for opening day of the annual Comic-Con International in San Diego, California, United States July 21, 2016. (Photo by Mike Blake/Reuters)

Kandy Freeman participates in a Black Lives Matter protest in front of Trump Tower in New York City, U.S. January 14, 2017. (Photo by Stephanie Keith/Reuters)

A spectator cools herself at a water spraying fan at the Australian Open tennis championships in Melbourne, Australia, Tuesday, January 17, 2017. (Photo by Kin Cheung/AP Photo)

This picture taken on February 16, 2017 in Fangshan village in China's coastal province Fujians, shows a villager performing the “eating flowers” ritual. Villagers in eastern China have a unique way of washing away the taint of evil spirits – by bathing in a shower of scorching sparks. (Photo by Johannes Eisele/AFP Photo)

Brain-on-a-chip. Dazzling in green and magenta this image shows the nerve fibres (in green) produced by neural stem cells (in magenta) as they grow on a synthetic gel. Captured by a technique known as confocal microscopy, the image is part of research shedding light on how tinkering with the environment can affect the way in which nerve fibres grow. (Photo by Collin Edington and Iris Lee/Massachusetts Institute of Technology/Wellcome Images)

Aldi SugandaRizal (2 years-old) smoking a cigarette while playing at the family home in Sekayu district, South Sumatera, Indonesia on May 23, 2010. (Photo by Ardiles Rante/Barcroft Media)

A firefighter rests next to fire combat truck during a wildfire at Penela, Coimbra, central Portugal, on June 18, 2017. A wildfire in central Portugal killed at least 25 people and injured 16 others, most of them burning to death in their cars, the government said on June 18, 2017. Several hundred firefighters and 160 vehicles were dispatched late on June 17 to tackle the blaze, which broke out in the afternoon in the municipality of Pedrogao Grande before spreading fast across several fronts. (Photo by Patricia De Melo Moreira/AFP Photo)

A person poses on the track during a fashion competition at the Durban July horse racing event in Durban, South Africa July 1, 2017. (Photo by Rogan Ward/Reuters)