How can I explicitly qualify things from module?

[Cpluspluser]

Hello everybody.

In C++ it is considered good practice to qualify names in 
namespaces, as in:

std::vector<int> v;
std::cout << std::endl;

How can this be done in D, with its std module?
For example I tried the following and it doesn't work.

import std.stdio;

void main()
{
     std.writeln("Hello world!");
}

Thank you for your time.