code: def filter(self, chromosome, **kwargs) :
  		
  		def appendAllele(alleles, sources, snp) :
  			pos = snp.start
  			if snp.alt[0] == '-' :
  				pass
  				# print warn % ('DELETION', snpSet, snp.start, snp.chromosomeNumber)
  			elif snp.ref[0] == '-' :
  				pass
  				# print warn % ('INSERTION', snpSet, snp.start, snp.chromosomeNumber)
  			else :
  				sources[snpSet] = snp
  				alleles.append(snp.alt) #if not an indel append the polymorphism
  			
  			refAllele = chromosome.refSequence[pos]
  			alleles.append(refAllele)
  			sources['ref'] = refAllele
  			return alleles, sources
  				
  		warn = 'Warning: the default snp filter ignores indels. IGNORED %s of SNP set: %s at pos: %s of chromosome: %s'
  		sources = {}
  		alleles = []
  		for snpSet, data in kwargs.iteritems() :
  			if type(data) is list :
  				for snp in data :
  					alleles, sources = appendAllele(alleles, sources, snp)
  			else :
  				allels, sources = appendAllele(alleles, sources, data)
  
  		#appends the refence allele to the lot
  
  		#optional we keep a record of the polymorphisms that were used during the process
  		return SequenceSNP(alleles, sources = sources)
docs: The default filter mixes applied all SNPs and ignores Insertions and Deletions.