code: public EvolutionDurations plus(final EvolutionDurations other) {
  		requireNonNull(other);
  		return of(
  			_offspringSelectionDuration.plus(other._offspringSelectionDuration),
  			_survivorsSelectionDuration.plus(other._survivorsSelectionDuration),
  			_offspringAlterDuration.plus(other._offspringAlterDuration),
  			_offspringFilterDuration.plus(other._offspringFilterDuration),
  			_survivorFilterDuration.plus(other._survivorFilterDuration),
  			_evaluationDuration.plus(other._evaluationDuration),
  			_evolveDuration.plus(other._evolveDuration)
  		);
  	}
docs: Returns a copy of this duration with the specified duration added.
  <p>
  This instance is immutable and unaffected by this method call.
  
  @param other the duration to add
  @return a {@code EvolutionDurations} based on this duration with the
  specified duration added
  @throws NullPointerException if the {@code other} duration is {@code null}
  @throws ArithmeticException if numeric overflow occurs