public UDFParameterValidator validateInputSeriesNumber(int expectedSeriesNumber)
      throws UDFInputSeriesNumberNotValidException {
    int actualSeriesNumber = parameters.getChildExpressionsSize();
    if (actualSeriesNumber != expectedSeriesNumber) {
      throw new UDFInputSeriesNumberNotValidException(actualSeriesNumber, expectedSeriesNumber);
    }
    return this;
  }
Validates whether the number of the input series is as expected.

@param expectedSeriesNumber the expected number of the input series
@throws UDFInputSeriesNumberNotValidException if the number of the input series is not as
    expected
iotdb-api/udf-api/src/main/java/org/apache/iotdb/udf/api/customizer/parameter/UDFParameterValidator.java