yaml overlay

[T. Onoma]

this has come up again for me, is their an easy way to overlay yaml documents?

ex-

---
a:
i: 1
ii: two
b:
- 1
- 2
---
a:
ii: 2
iii: 3
b:
- 3

overlayed becomes:

---
a:
i: 1
ii: 2
iii: 3
b:
- 1
- 2
- 3

Basically the overlay rules are 1) append collecitons 2) replace scalars

Thanks