code: public BioCLocation getTotalLocation() {
      checkArgument(getLocationCount() > 0, "No location added");
      RangeSet<Integer> rangeSet = TreeRangeSet.create();
      for (BioCLocation location : getLocations()) {
        rangeSet.add(
            Range.closedOpen(location.getOffset(), location.getOffset() + location.getLength()));
      }
      Range<Integer> totalSpan = rangeSet.span();
      return new BioCLocation(totalSpan.lowerEndpoint(),
          totalSpan.upperEndpoint() - totalSpan.lowerEndpoint());
    }
docs: Returns the minimal range which encloses all locations in this annotation.
  
  @return the minimal range which encloses all locations in this annotation