class BeamSqlStringUnaryExpression extends BeamSqlExpression {

  @Override
  public boolean accept() {
    if (operands.size() != 1) {
      return false;
    }

    if (!SqlTypeName.CHAR_TYPES.contains(opType(0))) {
      return false;
    }

    return true;
  }

  public  BeamSqlStringUnaryExpression(List<BeamSqlExpression> operands, SqlTypeName outputType);

}