I would like to be able to include one file inside another, but have the contents of the included file all indented by a certain amount. For example:

test.inc

multiline
example

test.yaml

example:
  content: |
    #include_indented test.inc
  other: asdf

Intended result:

example:
  content: |
    multiline
    example
  other: asdf

I am not sure if this is currently possible with gpp only? If so, I couldn't figure out how. Perhaps there's a way to use the output of include in a macro to then prefix all the lines with a string?

The only solution I could come up with so far is using exec, which I would prefer to avoid if possible.