gistfile1.py

# global scope these variables so that
# we can use them throughout our code
Car = None
Bus = None

#
# exciting stuff happening here
#

# now, based on the variable vehicle
# we want to import a specific module
if vehicle == "car":
    # equivalent to: from vehicle.four_wheels.car import Car
    _Car = __import__("vehicle.four_wheels.car", globals(), locals(), ["Car"])
    Car  = _Car.Car
if vehicle == "bus":
    # equivalent to: from vehicle.four_wheels.bus import Bus
    _Bus = __import__("vehicle.four_wheels.bus", globals(), locals(), ["Bus"])
    Bus  = _Bus.Bus