Tag Finder

import os
file = open('sample.txt', 'r', encoding = "utf8")
data = file.read()
keys = ['Shingeki no Kyojin', 'To Aru Kagaku no Railgun S']
tags = ("<tr", "</tr>", "<td", "</td>")

ctr = []
ftr = []
ctd = []
ftd = []

def encontraTD(n):
        comeco = data.find(tags[2],n)
        fim = data.find(tags[3],n)
        return [comeco,fim]

def encontraTR(n):
    comeco = data.find(tags[0],n)
    fim = data.find(tags[1],n)
    ctr.append(comeco)
    ftr.append(fim)
    return [comeco,fim]

FUNCIONA = True
lastTR = 0
while(FUNCIONA):
        gotTR = encontraTR(lastTR)
        lastTR = gotTR[1]+1
        print(gotTR)
        if len(data) - gotTR[1] < 10:
                break

print("ctr: " + str(ctr))
print("ftr: " + str(ftr))
file.close()