svoid cMigrateField(Concept c, S oldField, S newField) {
  if (c == null) ret;
  O oldValue = cget(c, oldField);
  O newValue = cget(c, newField);
  if (oldValue != null && newValue == null) pcall {
    S name = shortDynName(c);
    print("Migrating " + name + "." + oldField + " -> " + name + "." + newField + " [id " + c.id + "]");
    cset(c, newField, oldValue);
    cset(c, oldField, null);
  }
}