Test for an empty directory that could be very large if it is not empty?

[Virgil Stokes]

Suppose I have a directory C:/Test that is either empty or contains more 
than 2000000 files, all with the same extension (e.g. *.txt). How can I 
determine if the directory is empty WITHOUT the generation of a list of 
the file names in it (e.g. using os.listdir('C:/Test')) when it is not 
empty?