code: public Histogram<T> setSignificantFigures( int significantFigures ) {
          if (significantFigures != this.significantFigures) {
              this.significantFigures = significantFigures;
              this.bucketWidth = null;
              this.buckets.clear();
          }
          return this;
      }
docs: Set the number of significant figures used in the calculation of the bucket widths.
  
  @param significantFigures the number of significant figures for the bucket widths
  @return this histogram, useful for method-chaining
  @see #DEFAULT_SIGNIFICANT_FIGURES