gistfile1.txt

text = "ab[ffffff]cd[-]ef"
print("length: {0}".format(len(text)))
#print(text[2])                                                                                                                                               
indexes = [0,2,10,12,15,17]

for i in range(0, len(indexes) / 2):
    sindex = indexes[i*2]
    eindex = indexes[i*2+1]
    print("s: {0}".format(sindex))
    print("e: {0}".format(eindex))
    for x in range(sindex, eindex):
        current = text[x]
        print("current: {0}".format(current))
        next = None
        if (sindex < x+1 < eindex):
            next = text[x+1]
        elif x+1 == eindex:
            if not len(indexes) == i*2+2:
                nextIndex = indexes[i*2+2]
                next = text[nextIndex]
        print("next: {0}".format(next))