def get_elementary_intervals(self, features):
        coords = []
        try:
            for interval in features:
                if len(interval) != 3:
                    raise SyntaxError('Interval malformed %s. Allways specify start and end position for interval.' % str(interval))
                coords.extend([interval[0],interval[1]])    
        except IndexError:
            raise SyntaxError('Interval malformed %s. Allways specify start and end position for interval.' % str(interval))
        coords = list(set(coords))
        coords.sort()
        return coords