code: def sam_list(sam):
  	
  	list = []
  	for file in sam:
  		for line in file:
  			if line.startswith('@') is False:
  				line = line.strip().split()
  				id, map = line[0], int(line[1])
  				if map != 4 and map != 8:
  					list.append(id)
  	return set(list)
docs: get a list of mapped reads