Street fighting in Berlin between Government troops and Spartacists, during the Spartacist uprising which followed Germany's defeat in World War I. (Photo by Keystone/Getty Images). 1919

In this picture taken on September 24, 2016, relatives grieve their lost one, an alleged drug user/dealer gunned down by unidentified gunmen in Manila. Philippine President Rodrigo Duterte defended his threat to kill criminals as “perfect” and vowed no let-up in his war on crime, as the death toll surged past 3,700. (Photo by Noel Celis/AFP Photo)

A frog sits on a leaf and instead of seeing a reflection of itself in the water below, it sees a snail, attached to the bottom of the leaf, in a fish tank in Vietnam. (Photo by Duong Quoc Dinh/Solent Ne/SIPA Press)

A worker applies colour to strings which will be used to fly kites, by a roadside in Ahmedabad, India, November 23, 2017. (Photo by Amit Dave/Reuters)

Ukrainians jump over a fire in Kiev, Ukraine, 06 July 2017, as they celebrate the traditional pagan holiday of Ivana Kupala. Ivana Kupala is celebrated, during the summer solstice, on the shortest night of the year, marking the beginning of summer and is celebrated in Ukraine, Belarus, Poland and Russia on the night of 06 July. People sing and dance around bonfires, play games and perform traditional rituals. Young people jump over bonfires in order to test their bravery. Couples holding hands jump over the flames to test their love. If the couple does not succeed it is predicted to split up. Traditionally, children and young unmarried women wear wreaths of wild flowers on their heads to symbolize purity. (Photo by Sergey Dolzhenko/EPA)

Tourists dressed in yukatas, a light, unlined, summer kimono made of cotton instead of the traditional silk, climb steps to visit a temple on April 27, 2016 in Kyoto, Japan. Now the seventh largest city in Japan, Kyoto was once the Imperial capital for more than one thousand years, it is now the capital city of Kyoto Prefecture and a major part of the Kyoto-Osaka-Kobe metropolitan area. (Photo by Carl Court/Getty Images)

A man covered with dust sits on a street following a reported air strike by Syrian government forces in the rebel-held neighbourhood of Sukkari in the northern city of Aleppo on May 30, 2016. (Photo by Baraa Al-Halabi/AFP Photo)

Members of the staff wait for the start of the maiden press conference for China's all-girl “boyband” FFC-Acrush in Beijing, China April 28, 2017. Picture taken April, 28, 2017. (Photo by Damir Sagolj/Reuters)