Armed Yemeni children sit in the back of a pick up truck with fighters loyal to Yemen's Saudi-backed President Abedrabbo Mansour Hadi in the Dar saad neighbourhood of the southern Yemeni city of Aden on May 10, 2015, as they continue to battle Shiite Huthi rebels. (Photo by Saleh Al-Obeidi/AFP Photo)

A tearful Beatle lover pleads unsuccessfully with a policeman to carry her fan button to Ringo, one of the four mop-top singers who drew squeals and shrieks from more than 30,000 spectators at two Indiana State Fair shows in Indianapolis on September 4, 1964. (Photo by Bob Daugherty/AP Photo)

A Tibetan artists wearing a traditional costume waits before their performance during the 82nd pre-birthday celebration of Tibetan spiritual leader Dalai Lama at a Monastery in Kathmandu, Nepal, 05 July 2017. More than 1,000 monks and other Tibetans gathered at the Monastery compound to celebrate their spiritual leader's birthday. The Nepalese government has banned all kinds of Tibetan activities against the Chinese rule in Tibet so Tibetans have been changing the venue of the Dalai Lama's birthday celebration. The Dalai Lama will turn 82 on 06 July 2017. (Photo by Narendra Shrestha/EPA)

This image made available by the Johns Hopkins University Applied Physics Laboratory on Wednesday, May 31, 2017 depicts NASA's Solar Probe Plus spacecraft approaching the sun. On Wednesday, NASA announced it will launch the probe in summer 2018 to explore the solar atmosphere. It will be subjected to brutal heat and radiation like no other man-made structure before. (Photo by Johns Hopkins University Applied Physics Laboratory via AP Photo)

A man looks at kebabs cooking on the street side in Rawalpindi, Pakistan October 2, 2017. (Photo by Caren Firouz/Reuters)

An undated handout image provided by UNICEF Germany on 20 December 2016 shows the “UNICEF Photo of the Year 2016” by Iranian freelance photographer Arez Ghaderi. Ghaderi won the first prize for his picture of a girl in a makeshift tent city in the Razavi Khorasan province, Iran, it was announced at a ceremony in Berlin, Germany on 20 December 2016. (Photo by Ariz Ghaderi/EPA/UNICEF Deutschland)

California “weed nun” Christine Meeusen, 57, (R), and India Delgado, who goes by the name Sister Eevee, smoke a joint at Sisters of the Valley near Merced, California, April 18, 2017. (Photo by Lucy Nicholson/Reuters)

Five-month-old baby elephant Fah Jam swims during a hydrotherapy treatment as part of a lengthy rehabilitation process to heal her injured front left foot at a rehabilitation center in Pattaya, Thailand January 5, 2017. The baby elephant was injured at three months old when she got stuck in an animal snare put up by villagers to prevent elephant intrusions in Chanthaburi province. (Photo by Athit Perawongmetha/Reuters)