[
 {
  "name": "calc_aliens",
  "expr": "sorted(doc.Sheets.getByIndex(0).getCellByPosition(0, 0).UserDefinedAttributes.ElementNames)",
  "expect": [
   "ex:alien-foreign"
  ]
 },
 {
  "name": "calc_aliens_foreign",
  "expr": "[n for n in sorted(doc.Sheets.getByIndex(0).getCellByPosition(0, 0).UserDefinedAttributes.ElementNames) if n.startswith('ex:')]",
  "expect": [
   "ex:alien-foreign"
  ]
 }
]