How to correct this for loop over tuple function in Python? -

here program each line split pairs using tuples, such every alphabet had corresponding numeric a:6, b:6, c:35 ..etc if value less 10, alphabets converted n. following code. find code not loop on tuple function in last part of code. takes in single sequence , not loop on other

tutorial = open('c:/test/z.txt','r') ## input file looks >qrst abcde--  6  6 35 25 10 >qqqq abbde--  7  7 28 29  2  org = [] seqlist = [] seqstring = "" line in tutorial:     if line.startswith(">"):         if seqstring!= "":             seqlist.append(seqstring)             seqstring = ""         org.append(line.rstrip("\n"))     else:         seqstring += line.rstrip("\n") seqlist.append(seqstring) l = seqlist #print l  j = [] ll = len(seqlist) in range(0,ll):     sq = l[i]     sequence = sq.split(" ")[0] ## stores alphabets     qualities = sq.split(" ")[1:] ## stores numeric     qualities = filter(none, qualities)     sub in sequence:         if sub == "-": ## if sequences have "-", inserts "0" in position in corresponding number             idx = list(sequence).index(sub)             qualities.insert(idx,"0")  # error in steps below pairs = [] sub in l:     print sub     new_list = []     x in range(len(sequence)):         print x         new_tuple = (sequence[x], qualities[x]) #printing step, notice 1 of sequences printed twice. error         print new_tuple         if int(qualities[x]) < 10:             new_tuple = ("z",   qualities[x])          new_list.append(new_tuple)     pairs.append(new_list) print pairs # when print pairs looks this: [[('z', '7'), ('z', '7'), ('b', '28'), ('d', '29'), ('z', '2'), ('z', '0'), ('z', '0')], [('z', '7'), ('z', '7'), ('b', '28'), ('d', '29'), ('z', '2'), ('z', '0'), ('z', '0')]] # sequence#2 printed twice over. first 1 not taken in 

all_inputs = []  # <---- add in range(0,ll):     sq = l[i]     sequence = sq.split(" ")[0] ## stores alphabets     qualities = sq.split(" ")[1:] ## stores numeric     qualities = filter(none, qualities)     sub in sequence:         if sub == "-":             idx = list(sequence).index(sub)             qualities.insert(idx,"0")     # add ***********************     all_inputs.append((sequence, qualities))  pairs = [] # change ******************************* sequence, qualities in all_inputs:     print sub      new_list = []     x in range(len(sequence)):         print x         new_tuple = (sequence[x], qualities[x])          print new_tuple         if int(qualities[x]) < 10:              new_tuple = ("z",   qualities[x])          new_list.append(new_tuple)     pairs.append(new_list) print pairs 

gives:

[[('z', '6'), ('z', '6'), ('c', '35'), ('d', '25'), ('e', '10'), ('z', '0'), ('z', '0')], [('z', '7'), ('z', '7'), ('b ', '28'), ('d', '29'), ('z', '2'), ('z', '0'), ('z', '0')]]