code: public Interval getInterval(String aName, int aLength) {
  		Interval interval = intervalsByName.get(aName);
  		if (interval == null)
  			interval = createInterval(aName, aLength);
  		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 and length.
  TODO: This method should be renamed to "getOrCreateInterval" or something like that
  TODO: This method MUST be synchonrized to avoid doublicate Interval instances....
  
  @param aName the Interval name
  @param aLength the length of the new Interval in seconds.
  @return the existing Interval or a new Interval with given name and length