Some hackery to make it easier to define things you want to iterate over.

structstuff.yaml

#@ load("@ytt:struct", "struct")
#@ load("@ytt:yaml", "yaml")


#@ def stuff():
crd:
- group: cert-manager.io
  kind: ClusterIssuer
  version: v1
- group: secretgen.carvel.dev
  kind: SecretExport
  version: v1alpha1
- group: secretgen.carvel.dev
  kind: SecretExport
  version: v1alpha1
#@ end

#@ later_crds = struct.encode(yaml.decode(yaml.encode(stuff()))).crd

#@ for later_crd in later_crds:
---
sample: #@ later_crd.group
#@ end