Input step does not seem to support `output { ... }` block?

[e-gineer]

I created an input step with an output block:

  step "input" "approve" {
    notifier = notifier[param.approvers[0]]

    type = "button"

    subject = param.subject

    prompt = param.prompt

    option "approve" {
      label = "Approve"
      style = "ok"
    }

    option "deny" {
      label = "Deny"
      style = "alert"
    }

    loop {
      until = result.value == "deny" || loop.index >= length(param.approvers)
      notifier = notifier[param.approvers[loop.index]]
    }

    output "approved" {
      value = self.value == "approve"
    }

  }

But, I don't see the output from the step in the log?

[approve.approve[0]] Starting input: http://localhost:7003/form/co23peso47mt2en5rbe0/0oqgj50m3e00d
[approve.approve[0]] Arg cc = 
[approve.approve[0]] Arg notifier = {
  "notifies": [
    {
      "integration": {
        "type": "http"
      }
    }
  ]
}
[approve.approve[0]] Arg options = [
  {
    "label": "Approve",
    "style": "ok",
    "value": "approve"
  },
  {
    "label": "Deny",
    "style": "alert",
    "value": "deny"
  }
]
[approve.approve[0]] Arg prompt = Should I square 2?
[approve.approve[0]] Arg subject = Should I square 2?
[approve.approve[0]] Arg to = 
[approve.approve[0]] Arg type = button
[approve.approve[0]] Attr value = approve
[approve.approve[0]] Complete 8s