@Override
		public String toString() {
			return "Partition[interval=%s, separators=%s]"
				.formatted(interval, Arrays.toString(separators));
		}
Return the index of the interval the given {@code value} belongs to.
If the value is smaller than the partition interval, -1 is returned.
If it is greater than the partition interval, {@link #size()} is
returned.

@param value the value to test
@return the interval index
@throws IllegalArgumentException if the value is {@link Double#NaN}
jenetics.incubator/src/main/java/io/jenetics/incubator/stat/Histogram.java