Try to gracefully handle a missing module, but raise if that module itself tries to import something that isn't available

gistfile1.py

try:
    module = __import__(name, **specs)
except ImportError:
    # If tracback "length" is greater than 1, there is most
    # probably a deeper ImportError that we don't want to
    # mask (example: missing library used by the base import)
    _, _, tb = sys.exc_info()
    if len(traceback.extract_tb(tb)) > 1:
        raise
    # else, handle the error graciously
    print('WARN: module %s is missing' % name)