Pakistani boys cool themselves off during a heat wave in Karachi, Pakistan, Wednesday, May 18, 2016. Various parts of the country continued to experience an intense heat wave, with the temperatures reaching 49 degree Celsius (120 Fahrenheit) in Larkana and other cities. (AP Photo/Fareed Khan)

Fareed Khan/AP

Pakistani boys cool themselves off during a heat wave in Karachi, Pakistan

TOPSHOT - An overloaded car travels through the Assaga refugee camp in Diffa on May 17, 2016, close to the Niger-Nigeria border.  Chief of Humanitarian Operations of the UN, Stephen O'Brien, vowed on May 17 to raise funds at the next World Humanitarian Summit for "significant" help to the more than 240,000 refugees displaced by Boko Haram in camps in south-east Niger. / AFP PHOTO / BOUREIMA HAMABOUREIMA HAMA/AFP/Getty Images

Boureima Hama/AFP

An overloaded car travels through the Assaga refugee camp in Diffa close to the Niger-Nigeria border

Queen Elizabeth II leaves Buckingham Palace, London, ahead of the State Opening of Parliament. PRESS ASSOCIATION Photo. Picture date: Wednesday May 18, 2016. See PA story POLITICS Speech. Photo credit should read: Dominic Lipinski/PA Wire

Dominic Lipinski/PA

Queen Elizabeth II leaves Buckingham Palace, London, ahead of the State Opening of Parliament 

Workers sit as they take a break near a banner of a new apartment in Jakarta, Indonesia, May 18, 2016. REUTERS/Beawiharta

Beawiharta/Reuters

Workers sit as they take a break near a banner of a new apartment in Jakarta, Indonesia

epa05313534 A photograph made available on 18 May 2016 shows substitutes reacting after their team-mates scored a goal during the first school football tournament, in the rebel-held city of Douma, Syria, 20 April 2016. Twelve teams took part in the first school football tournament that started on 16 April 2016. Ten days later the tournament was postponed after the fragile ceasefire between the government and rebel groups was breached by a wave of violence and several parts of Eastern Ghouta were targeted by government shelling. The final match was held on 14 May and al-Hekma school team snatched the title after beating al-Rowad school.  EPA/MOHAMMED BADRA

Mohammed Badra/EPA

Substitutes react after their team-mates scored a goal during the first school football tournament, in the rebel-held city of Douma, Syria 

Senator Bernie Sanders, an independent from Vermont and 2016 Democratic presidential candidate, speaks during a campaign event in Carson, California, U.S., on Tuesday, May 17, 2016. Sanders won the Democratic presidential primary in Oregon Tuesday while Hillary Clinton claimed victory in a closely fought contest in Kentucky, a split decision that will do little to change the nomination race but may delay the party from focusing on the general election. Photographer: Patrick T. Fallon/Bloomberg *** Local Caption *** Bernie Sanders

Patrick T. Fallon/Bloomberg

Senator Bernie Sanders, an independent from Vermont and 2016 Democratic presidential candidate, speaks during a campaign event in Carson, California 

A man stands in a building earmarked for demolition in the Mathare neighbourhood of Nairobi, Kenya, May 17, 2016. Kenya's authorities tore down a badly built residential block in the poor Nairobi district on Tuesday, one of more than 250 shoddy buildings that could now face demolition after a six-story structure collapsed this month killing 51 people. REUTERS/Goran Tomasevic SEARCH "MATHARE DEMOLITION" FOR THIS STORY. SEARCH "THE WIDER IMAGE" FOR ALL STORIES   TPX IMAGES OF THE DAY

Goran Tomasevic/Reuters

A man stands in a building earmarked for demolition in the Mathare neighbourhood of Nairobi, Kenya. Kenya’s authorities tore down a badly built residential block in the poor Nairobi district on Tuesday, one of more than 250 shoddy buildings that could now face demolition after a six-story structure collapsed this month killing 51 people.

Artists, Jeff Koons and Damien Hirst pose during a photocall to launch the Newport Street Gallery in London with Koon's piece "Play-Doh".

Charlie Bibby/FT

Artists, Jeff Koons and Damien Hirst pose during a photocall for the exhibition ‘Now’ with Koon’s piece Play-Doh at Newport Street Gallery in London 

LONDON, ENGLAND - MAY 17:  UKIP leader Nigel Farage and Jacob Rees-Mogg MP speak ahead of the Bruges Group press conference on May 17, 2016 in London, England. The event focused on the issues surrounding the European Arrest Warrant and how Britain would be, in the opinion of the speakers, better placed outside of the European Union.  (Photo by Dan Kitwood/Getty Images)

Dan Kitwood/Getty

UKIP leader Nigel Farage and Jacob Rees-Mogg MP speak ahead of the Bruges Group press conference in London, England. The event focused on the issues surrounding the European Arrest Warrant and how Britain would be, in the opinion of the speakers, better placed outside of the European Union

epa05311531 An activist of the lesbian, gay, bisexual and transgender (LGBT) movement named 'Sister Dominique' in front of a rainbow flag during an event held in front of the state parliament in Potsdam, Germany, 17 May 2016. The rainbow flag is flying in front of the Brandenburg state parliament on the same day. The flag has been popularised worldwide as a symbol of the LGBT movement.  EPA/RALF HIRSCHBERGER

Ralf Hirschberger/EPA

An activist of the lesbian, gay, bisexual and transgender (LGBT) movement named ‘Sister Dominique’ in front of a rainbow flag during an event held in front of the state parliament in Potsdam, Germany 

CHANGZHOU, CHINA - MAY 12:  A worker takes samples for quality of molten iron outside a furnace at the Zhong Tian (Zenith) Steel Group Corporation on May 12, 2016 in Changzhou, Jiangsu. Zhong Tian (Zenith) Steel Group Corporation is a privately-owned manufacturer that employs over 13,000 workers at its facility in China's eastern Jiangsu province. Since 2001, the company says it has adopted new technology to streamline the production of premium quality steel and to reduce environmental impact. The majority of its steel output is for the Chinese market with 20% earmarked for export, mostly to Asia. The company says it is profitable, but admits business has dropped marginally from past years. China is the world's largest steel producer, accounting for over 50% of global supply. China's government has vowed to cut production capacity at state-owned enterprises by up to 150 million tonnes over five years to ease concerns of an oversupply on global markets. However, its efforts appear to be overshadowed by a recent increase in steel prices that has revived production at some Chinese facilities that had been closed down.  (Photo by Kevin Frayer/Getty Images)

Kevin Frayer/Getty

A worker takes samples for quality of molten iron outside a furnace at the Zhong Tian (Zenith) Steel Group Corporation in Changzhou, Jiangsu province, China

BEIJING, CHINA - MAY 16: (CHINA OUT) Aerial view of wide area of flowers near Shisanling reservoir in Changping District on May 16, 2016 in Beijing, China. Blooming flowers attracted visitors in Beijing.  (Photo by VCG/VCG via Getty Images)

VCG/VCG/Getty

Aerial view of wide area of flowers near Shisanling reservoir in Changping District in Beijing, China

Nepalese riot police stand guard as activists from the Federal Alliance (members of the Madhesi and ethnic communities) demonstrate against the government in Kathmandu on May 17, 2016.   Hundreds of members of Nepal's ethnic minorities blocked roads in renewed protests calling for changes to the Himalayan nation's controversial new constitution. / AFP PHOTO / PRAKASH MATHEMAPRAKASH MATHEMA/AFP/Getty Images

Prkash Mathema/AFP

Nepalese riot police stand guard as activists from the Federal Alliance (members of the Madhesi and ethnic communities) demonstrate against the government in Kathmandu 

Cast members Usher Raymond IV and Edgar Ramirez (L) pose during a photocall for the film "Hands of stone" out of competition at the 69th Cannes Film Festival in Cannes, France, May 16, 2016. REUTERS/Regis Duvignau

Regis Duvignau/Reuters

Cast members Usher Raymond IV and Edgar Ramirez pose during a photocall for the film “Hands of stone” out of competition at the 69th Cannes Film Festival in Cannes, France 

A man injured following clashes with Kenyan riot police officers, runs away from teargas, during a demonstration of Kenya's opposition supporters in Nairobi, on May 16, 2016.  Opposition protestors led by former Prime Minister Raila Odinga gathered outside the Indepedent Electoral and Boundaries Comission building to demand the dismissal of IEBC commissioners, after alleged bias towards the ruling Jubillee Alliance Party. / AFP PHOTO / CARL DE SOUZACARL DE SOUZA/AFP/Getty Images

Carl De Souza/AFP

A man injured following clashes with Kenyan riot police officers, runs away from teargas, during a demonstration of Kenya‘s opposition supporters in Nairobi

Pilgrims crowd around the Virgin of El Rocio during a procession around the shrine of El Rocio in Almonte, southern Spain, May 16, 2016. REUTERS/Marcelo del Pozo

Marcelo del Pozo/Reuters

Pilgrims crowd around the Virgin of El Rocio during a procession around the shrine of El Rocio in Almonte, southern Spain

A Sadhu or Hindu holy man combs his beard after taking a dip in the waters of Shipra river during Simhastha Kumbh Mela in Ujjain, India May 16, 2016. REUTERS/Jitendra Prakash     TPX IMAGES OF THE DAY

Jitendra Prakash/Reuters

A Sadhu or Hindu holy man combs his beard after taking a dip in the waters of Shipra river during Simhastha Kumbh Mela in Ujjain, India

LONDON, ENGLAND - MAY 16:  Sadiq Khan, the new Mayor of London waves to a member of the public as he campaigns outside Tooting Broadway Underground station with Labour Party candidate for the local by-election Rosena Allin-Khan on May 16, 2016 in London, England. Rosena Allin-Khan is a junior accident and emergency doctor and mother of two who grew up in the constituency where Sadiq Khan's election to London Mayor has prompted a by-election.  (Photo by Mary Turner/Getty Images)

Mary Turner/Getty

Sadiq Khan, the new Mayor of London waves to a member of the public as he campaigns outside Tooting Broadway Underground station with Labour Party candidate for the local by-election Rosena Allin-Khan in London

A woman uses a traditional fan to cool herself in the audience during a showing of the Rebecca Vallance collection during Fashion Week in Sydney, Australia, May 16, 2016. REUTERS/Jason Reed

Jason Reed/Reuters

A woman uses a traditional fan to cool herself in the audience during a showing of the Rebecca Vallance collection during Fashion Week in Sydney, Australia 

Men watch demonstrators from Afghanistan's Hazara minority during a protest in Kabul, Afghanistan May 16, 2016.

Mohammad Ismail/Reuters

Men watch demonstrators from Afghanistan’s Hazara minority during a protest in Kabul, Afghanistan