Former US president Barack Obama met New York Mayor Zohran Mamdani for the first time on Saturday at a child care centre where they read to preschoolers and led a singalong.The meeting comes as Mamdani, a democratic socialist who marked his 100th day in office just over a week ago, is also trying to build a working relationship with Republican US President Donald Trump.Obama and Mamdani did not take questions after reading the book Alone and Together to the children and leading a singalong of...