Using a python program with partial functionality if an import is unavailabe

I'm working on a program that needs to work with partial functionality if a package is not installed on a machine. Specifically it outputs a stream of data either as a TCP message or over ROS. On a machine that doesn't have ROS installed I would like to disable that option. My current solution is to wrap the optional functionality in a class that will initialize fully if an import succeeds and will return nothing if it is not

try:
    import rospy
    ros_available = True
except ModuleNotFoundError as e:
    print(e)
    ros_available = False

class ROSOutput:
    def __init__(self):
        self.ros_available = ros_available
        if not ros_available:
            return
        # if available- initialize

    def do_things():
        if not self.ros_available:
            return False # Nope
        # if available- do things

Can anyone suggest a smarter way to do this? Can I avoid defining a variable during imports?