code: private static Integer getEarliestTimestampLineIndex(List<LineAndTime> lines) {
  		Integer i = 0;
  		for (LineAndTime line : lines) {
  			if (isExactEarthTimestamp(line.getLine()))
  				return i;
  			else
  				i++;
  		}
  		return null;
  	}
docs: Returns the index of the earliest timestamp (PGHP) line. If none found
  returns null.
  
  @param lines
  @return