A woman carrying a bundle on her head wait in line to cross the border into Colombia through the Simon Bolivar bridge in San Antonio del Tachira, Venezuela, Sunday, July 17, 2016. Tens of thousands of Venezuelans crossed the border into Colombia on Sunday to hunt for food and medicine that are in short supply at home. It's the second weekend in a row that Venezuela’s government has opened the long-closed border connecting Venezuela to Colombia. (Photo by Ariana Cubillos/AP Photo)

Olivia Love-Hatlestad of Grayslake, IL., stands during the second day of the Democratic National Convention at the Wells Fargo Center, July 26, 2016 in Philadelphia, Pennsylvania. An estimated 50,000 people are expected in Philadelphia, including hundreds of protesters and members of the media. The four-day Democratic National Convention kicked off July 25. (Photo by Drew Angerer/Getty Images)

People stroll alongside one of the hills of the Tio Pio park in Madrid, Monday, January 25, 2016. The park is a high viewpoint frequented mostly by locals due to its view of the Spanish capital skyline. (Photo by Francisco Seco/AP Photo)

Refugee children play with a stuffed toy at a muddy makeshift camp at the Greek-Macedonian border, near the village of Idomeni, Greece March 15, 2016. (Photo by Alexandros Avramidis/Reuters)

Robot pianist Teo Tronico performs at the World Robot Conference (WRC) 2017 at Etrong International Exhibition & Convention Center on August 22, 2017 in Beijing, China. The World Robot Conference 2017 is held from August 23 to 27 in Beijing. (Photo by Liu Guanguan/China News Service/VCG via Getty Images)

A woman wades through a flooded village in the eastern state of Bihar, India August 22, 2017. (Photo by Cathal McNaughton/Reuters)

A Kenya Wildlife Services (KWS) veterinarian and security personnel back away from a tranquilised black-Rhino calf August 30, 2017 after she appeared to prematurely overcome the sedative at the Nairobi National Park, during an identification-tagging excercise to ease quick identification of resident rhino during anti-poaching patrols. (Photo by Tony Karumba/AFP Photo)

An injured young woman is led away after an incident at Parsons Green underground tube station in west London on September 15, 2017. Police and ambulance services said they were responding to an “incident” at Parsons Green underground station in west London on Friday, following media reports of an explosion. A Metro. co. uk reporter at the scene was quoted by the paper as saying that a white container exploded on the train and passengers had suffered facial burns. (Photo by Luke MacGregor/Reuters)