How to set default value to the key in YAML?

Ruby
1
  1. In case I have a key which comes with dictionary values but I also
    need
    to define the default value to that key.
    e.g.

key = default_value:
k1: v1
k2: v2

Some kind like this. Can I do that?

  1. If I can set the defualt value to key. How can I access that default
    value?