class BeamSqlLowerExpression extends BeamSqlStringUnaryExpression {

  @Override
  public BeamSqlPrimitive evaluate(
      Row inputRow, BoundedWindow window, ImmutableMap<Integer, Object> correlateEnv) {
    String str = opValueEvaluated(0, inputRow, window, correlateEnv);
    return BeamSqlPrimitive.of(SqlTypeName.VARCHAR, str.toLowerCase());
  }

  public  BeamSqlLowerExpression(List<BeamSqlExpression> operands);

}