private RelDataType[] collectOperandTypes(
     SqlValidator validator, SqlValidatorScope scope, SqlCall call) {
   RelDataType[] argTypes = SqlTypeUtil.deriveAndCollectTypes(validator, scope, call.operands);
   RelDataType[] newArgTypes = {
     argTypes[VALUE_OPERAND], argTypes[LOWER_OPERAND], argTypes[UPPER_OPERAND]
   };
   return newArgTypes;
 }