How can I do string concatenation, or string replacement in YAML?

Question

I have this:

user_dir: /home/user
user_pics: /home/user/pics

How could I use the user_dir for user_pics? If I have to specify

Answer 1

Seems to me that YAML itself does not define way to do this.

Good news are that YAML consumer might be able to understand variables.
What will use Your YAML?