Police are highly visible at the Notting Hill carnival with several arrests, stop and search and a “knife detection gate” in operation, August 27, 2018 in west London, England. 133 arrests were made at the carnival yesterday with 20 knives seized. (Photo by South West News Service/Action Press/Picturedesk)

A man rides a horse while others swim on the beach of Gaza City, Friday, August 3, 2018. (Photo by Khalil Hamra/AP Photo)

An artist dressed as demon King Ravana reacts as he participates in Vijaya Dashmi, or Dussehra festival celebrations in Chandigarh, India October 19, 2018. (Photo by Ajay Verma/Reuters)

Spectators pose for a selfie before the running of the Melbourne Cup at the Flemington Racecourse in Melbourne, Australia, Tuesday, November 6, 2018. (Photo by Andy Brownbill/AP Photo)

The secretive indri (Indri indri) of Madagascar, the largest living lemur. It is also critically endangered and highly evolutionarily distinct with no close relatives, which makes its branch one of most precarious on the mammal evolutionary tree. In the likely event that the indri goes extinct, we will lose 19m years of unique evolutionary history from the mammal tree of life. (Photo by Pierre-Yves Babelon/Aarhus University)

A candle burns during a vigil in Aotea Square to remember victims of the Paris attacks on November 14, 2015 in Auckland, New Zealand. According to reports, over 150 people were killed in a series of bombings and shootings across Paris, including at a soccer game at the Stade de France and a concert at the Bataclan theater. (Photo by Hannah Peters/Getty Images)

Valery Bystritskii, 10, gets a fellow student into a lock at Bunny's Gym in July 2015 in Winchester, Tennessee. (Photo by Mike Saliba/Barcroft USA)

A woman shields her face from the sun as she rides her scooter in Ahmedabad, India May 20, 2016. (Photo by Amit Dave/Reuters)