code: @Nonnull
    public StringComparator naturalStringComparator(final SimpleExtraction simpleExtraction)
    {
      Preconditions.checkNotNull(simpleExtraction, "simpleExtraction");
      if (simpleExtraction.getExtractionFn() != null
          || getColumnType(simpleExtraction.getColumn()) == ValueType.STRING) {
        return StringComparators.LEXICOGRAPHIC;
      } else {
        return StringComparators.NUMERIC;
      }
    }
docs: Return the "natural" {@link StringComparator} for an extraction from this row signature. This will be a
  lexicographic comparator for String types and a numeric comparator for Number types.
  
  @param simpleExtraction extraction from this kind of row
  
  @return natural comparator