code: public static String deepCleanSequence(String sequence) {
  	sequence = SequenceUtil.cleanSequence(sequence);
  	sequence = SequenceUtil.DIGIT.matcher(sequence).replaceAll("");
  	sequence = SequenceUtil.NONWORD.matcher(sequence).replaceAll("");
  	final Pattern othernonSeqChars = Pattern.compile("[_-]+");
  	sequence = othernonSeqChars.matcher(sequence).replaceAll("");
  	return sequence;
  	}
docs: Removes all special characters and digits as well as whitespace chars
  from the sequence
  
  @param sequence
  @return cleaned up sequence