Former student leader Joshua Wong walks out from prison after being jailed for his role in the Occupy Central movement, also known as "Umbrella Movement", in Hong Kong, China, June 17, 2019. Hong Kong democracy activist Joshua Wong walked free from prison on Monday after serving nearly five weeks for contempt of court, pledging to join a mass protest movement demanding that the city's Beijing-backed leader, Carrie Lam, to step down. REUTERS/Tyrone Siu

Former student leader Joshua Wong walks out from prison after being jailed for his role in the Occupy Central movement, also known as "Umbrella Movement", in Hong Kong, China, June 17, 2019. His release comes a day after organisers of the protest calling for Lam to quit over a controversial extradition bill said almost two million black-clad people joined Sunday's march to government offices. REUTERS/Tyrone Siu

Former student leader Joshua Wong walks out from prison after being jailed for his role in the Occupy Central movement, also known as "Umbrella Movement ", in Hong Kong, China, June 17, 2019. "I will join to fight against this evil law," said Wong, 22, who was one of the leaders of the 2014 "Umbrella" pro-democracy protests that blocked major roads in the Chinese-ruled city for 79 days. "I believe this is the time for her, Carrie Lam the liar, to step down." REUTERS/Tyrone Siu

Former student leader Joshua Wong walks out from prison after being jailed for his role in Occupy Central movement, also known as "Umbrella Movement", in Hong Kong, China, June 17, 2019. Before he was jailed, both Wong and his supporters had called for the Hong Kong government to scrap the extradition proposal. REUTERS/Tyrone Siu

Former student leader Joshua Wong walks out from prison after being jailed for his role in the Occupy Central movement, also known as "Umbrella Movement ", in Hong Kong, China, June 17, 2019. Wong was just 17 when he stood at the forefront of the broad civil disobedience movement that presented China's Communist Party rulers in Beijing with one of their biggest political challenges in decades. REUTERS/Tyrone Siu

Former student leader Joshua Wong walks out from prison after being jailed for his role in the Occupy Central movement, also known as "Umbrella Movement", in Hong Kong, China, June 17, 2019. Hong Kong democracy activist Joshua Wong walked free from prison on Monday after serving nearly five weeks for contempt of court, pledging to join a mass protest movement demanding that the city's Beijing-backed leader, Carrie Lam, to step down. REUTERS/Tyrone Siu