load_module("stl_extra")

auto x = List()
// push_back newly constructed return value that's non-copyable
x.push_front(async(fun(){}))

// push_front newly constructed return value that's non-copyable
x.push_front(async(fun(){}))



// push_back newly constructed return value that's non-copyable

var v = []
v.push_back(async(fun(){}))