How can I check if a prompt file exists?

Hi everyone. Is there any function in ccScript that lets me check for the
existence of an audio file?
I want my code to do something like this:

if FileExists("dr34.au")      # file contains the name of doctor n° 34.
then
    play TheNameOfTheDoctorIs.au
    play dr34.au
else
    play DoctorDoesntExist.au
endif

Thank you all
Roberto from Mendoza, Argentina