European Union flags flutter as uncertainty over Brexit continues, in London, Britain April 10, 2019. REUTERS/Gonzalo Fuentes

European Unions flags fly outside the European Commission headquarters in Brussels, Belgium, April 10, 2019. REUTERS/Yves Herman

European Union flags fly outside the European Commission headquarters in Brussels, Belgium, April 10, 2019. REUTERS/Yves Herman

European Union flags fly outside the European Commission headquarters in Brussels, Belgium, April 10, 2019. REUTERS/Yves Herman

A man waves a European flag at a rally held by The People's Vote, calling for another Brexit referendum, ahead of an EU summit, in London, Britain, April 9, 2019. REUTERS/Gonzalo Fuentes

European Union and British flags flutter in front of a chancellery ahead of a visit of British Prime Minister Theresa May in Berlin, Germany, April 9, 2019. REUTERS/Hannibal Hanschke

Small toy figures are seen in front of a Brexit logo in this illustration picture, March 30, 2019. REUTERS/Dado Ruvic/Illustration

Small toy figures are seen in front of a Brexit logo in this illustration picture, March 30, 2019. REUTERS/Dado Ruvic/Illustration

A small toy figure is seen in front of a Brexit logo in this illustration picture, March 30, 2019. REUTERS/Dado Ruvic/Illustration

Pro-Brexit protesters take part in the March to Leave demonstration, in London, Britain March 29, 2019. REUTERS/Toby Melville

EU supporters, calling on the government to give Britons a vote on the final Brexit deal, participate in the 'People's Vote' march in central London, Britain March 23, 2019. REUTERS/Kevin Coombs

An EU supporter, calling on the government to give Britons a vote on the final Brexit deal, participates in the 'People's Vote' march in central London, Britain March 23, 2019. REUTERS/Peter Nicholls

European Union flags fly outside the European Commission headquarters in Brussels, Belgium March 19, 2019 REUTERS/Yves Herman

European Union flags are seen at half-mast in tribute to the victims of the attack in Strasbourg, outside the European Commission headquarters in Brussels, Belgium, December 12, 2018. REUTERS/Francois Lenoir

Pro-Brexit supporters burn an EU flag during a UKIP demonstration in central London, Britain, December 9, 2018. REUTERS/Dylan Martinez

Protesters participating in an anti-Brexit demonstration march through central London, Britain October 20, 2018. REUTERS/Simon Dawson

A protester wears a beret before an anti-Brexit demonstration, in central London, Britain October 20, 2018. REUTERS/Simon Dawson

A protester wears badges pinned on jeans, before an anti-Brexit demonstration, in central London, Britain October 20, 2018. REUTERS/Simon Dawson

Pro-EU demonstrators wave flags outside the Houses of Parliament in Westminster London, Britain, July 17, 2018. REUTERS/Henry Nicholls TPX IMAGES OF THE DAY

Pro-EU supporters wave flags outside the Houses of Parliament in Westminster, London, Britain, July 4, 2018.REUTERS/Simon Dawson

A padlock stands on a displayed European Union flag in this illustration taken May 23, 2018. REUTERS/Dado Ruvic/Illustration

A padlock stands on a displayed EU flag in this illustration taken May 23, 2018. REUTERS/Dado Ruvic/Illustration

A padlock stands on a displayed EU flag in this illustration taken May 23, 2018. REUTERS/Dado Ruvic/Illustration

Flags of European Union and Poland are seen during an anti-government protest, called 'Freedom March' and organised by opposition parties, in Warsaw, Poland May 12, 2018. REUTERS/Kacper Pempel

The European Union flag flies in the County Kerry village Doora Cross, Ireland, May 5, 2018. REUTERS/Clodagh Kilcoyne

Thailand's Prime Minister Prayuth Chan-ocha arrives for a meeting with Jack Ma, founder of Chinese e-commerce giant Alibaba, in Bangkok, Thailand, April 19, 2018 during the latter's visit to the country to announce the group's investment in the Thai government's Eastern Economic Corridor (EEC) scheme. REUTERS/Jorge Silva/Pool

Jack Ma, founder of Chinese e-commerce giant Alibaba, shakes hands with Thailand's Prime Minister Prayuth Chan-ocha in Bangkok, Thailand, April 19, 2018 during a visit to the country to announce the group's investment in the Thai government's Eastern Economic Corridor (EEC) scheme. REUTERS/Jorge Silva/Pool

Jack Ma, founder of Chinese e-commerce giant Alibaba, meets Thailand's Prime Minister Prayuth Chan-ocha in Bangkok, Thailand, April 19, 2018 during a visit to the country to announce the group's investment in the Thai government's Eastern Economic Corridor (EEC) scheme. REUTERS/Jorge Silva/Pool

Jack Ma, founder of Chinese e-commerce giant Alibaba, gestures during a visit to announce the group's investment in the Thai government's Eastern Economic Corridor (EEC) scheme, in Bangkok, Thailand, April 19, 2018. REUTERS/Jorge Silva/Pool

Jack Ma, founder of Chinese e-commerce giant Alibaba, arrives for a meeting with Thailand's Prime Minister Prayuth Chan-ocha in Bangkok, Thailand, April 19, 2018 during a visit to the country to announce the group's investment in the Thai government's Eastern Economic Corridor (EEC) scheme. REUTERS/Jorge Silva/Pool

Jack Ma, founder of Chinese e-commerce giant Alibaba, arrives for a meeting with Thailand's Prime Minister Prayuth Chan-ocha in Bangkok, Thailand, April 19, 2018 during a visit to the country to announce the group's investment in the Thai government's Eastern Economic Corridor (EEC) scheme. REUTERS/Jorge Silva/Pool

Jack Ma, founder of Chinese e-commerce giant Alibaba, shakes hands with Thailand's Prime Minister Prayuth Chan-ocha in Bangkok, Thailand, April 19, 2018 during a visit to the country to announce the group's investment in the Thai government's Eastern Economic Corridor (EEC) scheme. REUTERS/Jorge Silva/Pool

Jack Ma, founder of Chinese e-commerce giant Alibaba, gestures as he arrives for a meeting with Thailand's Prime Minister Prayuth Chan-ocha in Bangkok, Thailand, April 19, 2018 during a visit to the country to announce the group's investment in the Thai government's Eastern Economic Corridor (EEC) scheme. REUTERS/Jorge Silva/Pool

Jack Ma, founder of Chinese e-commerce giant Alibaba, meets Thailand's Prime Minister Prayuth Chan-ocha in Bangkok, Thailand, April 19, 2018 during a visit to the country to announce the group's investment in the Thai government's Eastern Economic Corridor (EEC) scheme. REUTERS/Jorge Silva/Pool

Jack Ma, founder of Chinese e-commerce giant Alibaba, meets Thailand's Prime Minister Prayuth Chan-ocha in Bangkok, Thailand, April 19, 2018 during a visit to the country to announce the group's investment in the Thai government's Eastern Economic Corridor (EEC) scheme. REUTERS/Jorge Silva/Pool

Jack Ma, founder of Chinese e-commerce giant Alibaba, meets Thailand's Deputy Prime Minister Somkid Jatusripitak in Bangkok, Thailand, April 19, 2018 during a visit to the country to announce the group's investment in the Thai government's Eastern Economic Corridor (EEC) scheme. REUTERS/Jorge Silva/Pool

Jack Ma, founder of Chinese e-commerce giant Alibaba, smiles as he meets Thailand's Deputy Prime Minister Somkid Jatusripitak in Bangkok, Thailand, April 19, 2018 during a visit to the country to announce the group's investment in the Thai government's Eastern Economic Corridor (EEC) scheme. REUTERS/Jorge Silva/Pool

Jack Ma, founder of Chinese e-commerce giant Alibaba, meets Thailand's Deputy Prime Minister Somkid Jatusripitak in Bangkok, Thailand, April 19, 2018 during a visit to the country to announce the group's investment in the Thai government's Eastern Economic Corridor (EEC) scheme. REUTERS/Jorge Silva/Pool

A tattered European Flag flies on the seafront in Great Yarmouth, Britain, March 20, 2018. Picture taken March 20, 2018. REUTERS/Hannah McKay

European flag is pictured in Blagnac near Toulouse, France March 21, 2018. REUTERS/Regis Duvignau

Anti Brexit protesters demonstrate outside the Houses of Parliament in London, Britain December 11, 2017. REUTERS/Peter Nicholls

An EU flag and Union flag are seen flying together during an anti-Brexit protest near the Houses of Parliament in London, Britain, December 8, 2017. REUTERS/Toby Melville

An EU flag and Union flag are seen flying together during an anti-Brexit protest near the Houses of Parliament in London, Britain, December 8, 2017. REUTERS/Toby Melville

Fahd Al Rasheed, Group Chief Executive Officer of Emaar the Economic City (EEC), gestures during an interview with Reuters in Riyadh, Saudi Arabia, October 25, 2017. REUTERS/Hamad I Mohammed

Fahd Al Rasheed, Group Chief Executive Officer of Emaar the Economic City (EEC), attends an interview with Reuters in Riyadh, Saudi Arabia, October 25, 2017. REUTERS/Hamad I Mohammed

European Union flags are lowered at half-mast in honor of the victims of the Manchester attack, outside the European Commission headquarters in Brussels, Belgium May 23, 2017. REUTERS/Francois Lenoir

European Union flags are lowered at half-mast in honor of the victims of the Manchester attack, outside the European Commission headquarters in Brussels, Belgium May 23, 2017. REUTERS/Francois Lenoir

A man adjusts his tie at a Pro-Brexit event to celebrate the invoking of Article 50 after Britain's Prime Minister Theresa May triggered the process by which the United Kingdom will leave the European Union, in London, Britain March 29, 2017. REUTERS/Peter Nicholls TPX IMAGES OF THE DAY

A protester wearing a Europen Union flag themed beret takes part in an anti-Brexit demonstration after Britain's Prime Minister Theresa May triggered the process by which the United Kingdom will leave the Euopean Union, in Birmingham, Britain March 29, 2017. REUTERS/Darren Staples TPX IMAGES OF THE DAY

A Pro-EU supporter takes part in a gathering marking the Union's 60th anniversary in Madrid, Spain, March 25, 2017. REUTERS/Susana Vera

Protestors raise their arms under an European flag during a pro-EU demonstration as European Union leaders meet in downtown Rome, Italy, March 25, 2017. REUTERS/Alessandro Bianchi

Protestors cast their shadows over an European flag during a pro-EU demonstration as European Union leaders meet in downtown Rome, Italy, March 25, 2017. REUTERS/Alessandro Bianchi

European Union and British Union flags are seen blowing in the wind in London, Britain, March 20, 2017. REUTERS/Toby Melville

European Union and British Union flags are seen blowing in the wind in London, Britain, March 20, 2017. REUTERS/Toby Melville

A traffic sign is seen in front of European and Union flags in London, Britain, March 20, 2017. REUTERS/Stefan Wermuth

A traffic sign is seen in front of European and Union flags in London, Britain, March 20, 2017. REUTERS/Stefan Wermuth

A sticker on a car is seen near the Houses of Parliament in London, Britain, March 20, 2017. REUTERS/Stefan Wermuth

A sticker on a car is seen near the Houses of Parliament in London, Britain, March 20, 2017. REUTERS/Stefan Wermuth

Protesters demonstrate near the building where European far-right leaders meet, in Koblenz, Germany, January 21, 2017. Banner reads: "Human rights instead of right humans". REUTERS/Kai Pfaffenbach

European Union Foreign Policy Chief Federica Mogherini (R) listens to Tunisian Foreign Minister Khemaies Jhinaoui during the 4th EU-League of Arab States Ministerial meeting between Arab and European foreign ministers, to discuss the Syrian and Iraqi crises, at the Arab League Headquarters in Cairo, Egypt December 20, 2016. REUTERS/Amr Abdallah Dalsh