code: public String OutEx( Printer<T> printer )
  	{
  		String out = "";
  		for( int i = 0; i < periods.size(); i++ )
  		{
  			PeriodAssociative<T> period = periods.get( i );
  			out += "[" + period.getFrom() + "->" + period.getTo() + "] => " + printer.print( period.getValue() ) + "<br>";
  		}
  		return out;
  	}
docs: print string