[monit] check file - if missing to do XX? possible?

[Joe Shang]

I want to enable in monit, to check for a file, like

check file with path /home/thisfile.txt

And I want if the file does not exist to execute a script for me... etc.

Though what happens is monit doesn't even start cause that file does
not exist, how can get over this? are there different parameters?

Because I have other arguments that if file does exist, to check for
changed checksum, and if changed to run a certain script.

But what is most important to me, is to check if the file exist, and
if not.. well execute something.