[Puppet Users] How to create run stages from an ENC?

Hello,

Is there a way to create run stages using just an ENC? If so, how
would it look like in YAML format?

I was thinking about something like this, but the YAML parser we use
doesn't accept it and a colleague of mine said that maybe Puppet
support for this is missing too. Is it true?

stages:
yum:
before: 'main'

# and then it could be used like this:
classes:
yum:
stage: 'yum' # this works already as expected and the stage is
getting passed to the yum class, but how do I get the stage created
from the ENC?

Thanks,
Cristian