def extract_person_fullname(person):
  """Extracts the person's fullname or builds it if needed."""
  full_name_elt = person.find("FullName")
  if full_name_elt is None:
    return []
  full_name_list = set()
  for name in full_name_elt.findall("Text"):
    if name.text:
      full_name_list.add(name.text)
      return full_name_list
  return []