This 1950s photo provided by the Estate of Vivian Maier and John Maloof Collection shows Maier in a self-portrait as she looks into a storefront wearing a hat in New York. New research about Maier shows the enigmatic Chicago nanny was obsessive about honing her skills as a photographer starting in 1950. (Photo by Vivian Maier/Estate of Vivian Maier and John Maloof Collection via AP Photo)

The work entitled “Trip 1, Trip II, Trip III” by April Pine is pictured before dawn at Sculpture By The Sea at Bondi Beach on October 19, 2017 in Sydney, Australia. This year the outdoor exhibition celebrates its 21st birthday with 104 exhibiting artists from Australia and around the world and runs from the 19th October-5th November 2017. (Photo by Brook Mitchell/Getty Images)

Revelers march during the Greenwich Village Halloween Parade, Tuesday, October 31, 2017, in New York. (Photo by Andres Kudacki/AP Photo)

A passenger (L) gets inside a decorated matatu as other passengers wait for it to fill at night in the streets of Nairobi, Kenya, 24 March 2018. The Matatu culture is very big in Kenya, the minibuses are decorated with colorful graffiti inside and outside and most of them are equipped with TV screens, high-speed internet, and power sockets. (Photo by Daniel Irungu/EPA/EFE)

A novice monk holds a book during an inauguration ceremony at Jogye temple in Seoul, May 11, 2015. Ten children on Monday were given the opportunity to experience life as Buddhist monks by staying at the temple until Buddha's birthday in two weeks. The writing on the book reads, “Novice Monk Prayer”. (Photo by Thomas Peter/Reuters)

Female soldiers with their faces painted in the colours of the Venezuelan flag, march during a military parade to celebrate the anniversary of Venezuela's independence in Caracas, July 5, 2015. (Photo by Jorge Dan Lopez/Reuters)

An Iranian woman gestures as she celebrates in the streets following a nuclear deal with major powers, in Tehran July 14, 2015. Overcoming decades of hostility, Iran, the United States, and five other world powers struck a historic accord Tuesday to check Tehran's nuclear efforts short of building a bomb. The agreement could give Iran access to billions in frozen assets and oil revenue, stave off more U.S. military action in the Middle East and reshape the tumultuous region. (Photo by Reuters/TIMA)

One of the most significant challenges related to cancer in Nepal is the lack of awareness around the prognosis of the disease, as many patients, their families and even healthcare professionals consider cancer to be an incurable disease at any stage. This results in significant delays in bringing patients to hospitals, and high rates of advanced stage cancers and mortality. (Photo by Omar Havana)