How do I access a map key+value to use as input for a process?

How do I access a map key+value to use as input for a process?

Hi,

We've got a custom function that outputs a map containing 4 key-value pairs.  All four are IDs that we need to use elsewhere as inputs to other processes but I can't see how we select just one map item for the input to another process - The only option we get in the picker is to select the whole map variable as the input, which obviously won't work for an item expecting a single input of an integer.

I'm hoping we're missing something really obvious.  I've looked through the docs though and can't see anything.

Thanks,

Karl