let a1 = Variable<(Int, Int)>((0, 0)) // Expression type 'Variable<(Int, Int)>' is ambiguous without more context let a2 = Variable<(Int, Int)>.init((0, 0)) // 可let a1 = Variable<(Int, Int)>((0, 0)) // Expression type 'Variable<(Int, Int)>' is ambiguous without more context let a2 = Variable<(Int, Int)>.init((0, 0)) // 可