Map.Entry<Value,Value> entry = iter.next();
StringValue key = entry.getKey().toReprString(env);
StringValue value = entry.getValue().toReprString(env);
if (value.length() > 0 && value.charAt(0) == '@') {
StringValue fileName = value.substring(1);
Path path = env.lookup(fileName);
if (path == null || ! path.canRead()) {