Mob program access user's inventory

I'm trying to write a mob program that does different actions based on what objects the user has in their inventory. For example, the user might talk to a mobile and the mobile would say "I see you have an axe there, could I interest you in a sword" Is there an mp command or something that would allow me to check a users inventory?

Also how would the mobile then take or give an object to the user?

There's an ifcheck called iscarrying.

If that's not built into Smaug, it should be a snippet out there somewhere.