code: def encodePolymorphicNucleotide(polySeq) :
  	
  	
  	if type(polySeq) is types.StringType :
  		if polySeq.find("/") < 0 :
  			sseq = list(polySeq)
  		else :
  			sseq = polySeq.split('/')
  			
  	else :
  		sseq = polySeq
  	
  	seq = []
  	for n in sseq :
  		try :
  			for n2 in polymorphicNucleotides[n] :
  				seq.append(n2)
  		except KeyError :
  			seq.append(n)
  	
  	seq = set(seq)
  	
  	if len(seq) == 4:
  		return 'N'
  	elif len(seq) == 3 :
  		if 'T' not in seq :
  			return 'V'
  		elif 'G' not in seq :
  			return 'H'
  		elif 'C' not in seq :
  			return 'D'
  		elif 'A' not in seq :
  			return 'B'
  	elif len(seq) == 2 :
  		if 'A' in seq and 'G' in seq :
  			return 'R'
  		elif 'C' in seq and 'T' in seq :
  			return 'Y'
  		elif 'A' in seq and 'C' in seq :
  			return 'M'
  		elif 'T' in seq and 'G' in seq :
  			return 'K'
  		elif 'A' in seq and 'T' in seq :
  			return 'W'
  		elif 'C' in seq and 'G' in seq :
  			return 'S'
  	elif polySeq[0] in nucleotides :
  		return polySeq[0]
  	else :
  		raise UnknownNucleotide(polySeq)
docs: returns a single character encoding all nucletides of polySeq 
  	in a single character. PolySeq must have one of the following forms: 
  	['A', 'T', 'G'], 'ATG', 'A/T/G