rospy equivalent to ros::NodeHandle nh("namespace")

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I'm very new to ROS and am [slightly] more versed in python than C++, so that's the route I'm currently pursuing in my learning. One option that is shown in the C++ tutorials is how one would set a custom namespace or parent namespace :

You can also specify a parent NodeHandle and a namespace to append:

### adding the initialization call from above
ros::init(argc, argv, "my_node_name");

ros::NodeHandle nh1("ns1");
ros::NodeHandle nh2(nh1, "ns2");

In the python information, I've only ever seen this used, which I take as equivalent to ros::init():

rospy.init_node('my_node_name')

How would one put node my_node_name into a custom or parent namespace using rospy?