code: public static Collector<Sample, ?, SampleSummary>
  	toSampleSummary(final int parameterCount) {
  		require.positive(parameterCount);
  
  		return Collector.of(
  			() -> new SampleSummaryStatistics(parameterCount),
  			SampleSummaryStatistics::accept,
  			SampleSummaryStatistics::combine,
  			SampleSummary::of
  		);
  	}
docs: Return a {@link Collector} for creating a {@code SampleSummary} object.
  
  @param parameterCount the number of parameters of the samples
  @return a {@code SampleSummary} {@link Collector}
  @throws IllegalArgumentException if the given {@code parameterCount} is
  smaller than one