Using existing modules to determine whether to run a script?

[Kim Betti]

I've started looking into Ansible and I quite like it. 

Is it possible to run a shell script only if the yum module determines that a given package is -not- installed? 

Or in more general terms, is there a convenient way to leverage existing modules to decide whether or not to run a task?

[Brian Coca]

tasks/modules can register output register: var, you can use that in when: clause in all/any subsequent tasks.