code: public Interval getInterval(String aName) {
  		Interval interval = intervalsByName.get(aName);
  		if (interval == null) {
  			interval = createInterval(aName, IntervalNameParser.guessLengthFromName(aName));
  		}
  		return interval;
  	}
docs: This method retrieves an Interval with the given name. If no one could be found it will
  create a new Interval with given name - the length will be a guess.
  TODO: This method should be renamed to "getOrCreateInterval" or something like that
  TODO: This method MUST be synchonrized to avoid double Interval instances....
  
  @param aName the Interval name
  @return the existing Interval or a new Interval with given name and guessed length