(Python) Find out the genbank, fasta and cluster format from the file and print the nucleotides

fileReader.py

import os.path
import re


def is_cluster_format(line):
	cluster_format_matcher = re.compile(clusterFormat)
	cluster_format_result = cluster_format_matcher.findall(line)
	return cluster_format_result.__len__() > 0


def is_fasta_format(line):
	fasta_format_matcher = re.compile(faFormat)
	fasta_format_result = fasta_format_matcher.findall(line)
	return fasta_format_result.__len__() > 0


def is_gen_bank_format(line):
	for i in line:
		gen_bank_format_result = re.findall(genBankFormat, i)
		if gen_bank_format_result.__len__() > 0:
			return gen_bank_format_result.__len__() > 0

	return False


def get_the_genbank_lines(lines):
	string_to_process = ''
	patternFound = False
	for line in lines:
		if patternFound:
			string_to_process += line
		else:
			if re.findall(genBankFormat, line).__len__() > 0:
				patternFound = True

	string_to_process = string_to_process.replace('//', '').strip()

	string_to_process = re.sub(r'\b\d+\b', '', string_to_process).replace('\n', '').replace('\s', '').strip()
	listOfStr = string_to_process.split(" ")

	final_gb_format = ''
	for eachStr in listOfStr:
		if eachStr != '':
			final_gb_format += eachStr

	return final_gb_format


def count_characters(string_data):
	return len(string_data)


if __name__ == '__main__':

	while "true":

		faFormat = '^>'
		genBankFormat = 'ORIGIN\n'
		clusterFormat = '^seq\\d\t'

		fileName = raw_input("\nPlease enter a file name :  ").strip()
		try:
			inputFile = open(fileName)
		except IOError:
			print ("File does not exist. Please give a correct file path")
		else:

			print(inputFile.name)

			read_lines_from_file = tuple(inputFile.readlines())

			if is_fasta_format(read_lines_from_file[0].strip("\n")):
				sequence = ''
				sequenceCounter = 1

				print "is Fasta Format \n"

				for i in range(1, len(read_lines_from_file)):
					if is_fasta_format(read_lines_from_file[i].strip("\n")):

						actualSequence = sequence.replace('\n', '')
						print " Sequence : ", sequenceCounter, " Counter : ", count_characters(actualSequence)
						print actualSequence.replace('\r', '')
						sequenceCounter = sequenceCounter + 1

						sequence = ''
						continue
					else:
						sequence += read_lines_from_file[i]

				print " Sequence : ", sequenceCounter, " Counter : ", count_characters(
					sequence.replace('\n', ''))
				print sequence.replace('\n', '').replace('\r', '')

			elif is_cluster_format(read_lines_from_file[0].strip("\n")):
				sequence = ''
				sequenceCounter = 1

				print "is Cluster Format"

				for each_line in range(0, len(read_lines_from_file)):
					sequence = read_lines_from_file[each_line]
					actualSequence = sequence.replace('\n', '')
					actualSequence = re.sub(r'^.*\t', r'', actualSequence)
					print " Sequence : ", sequenceCounter, " Counter : ", count_characters(actualSequence)
					print actualSequence
					sequenceCounter = sequenceCounter + 1

			elif is_gen_bank_format(read_lines_from_file):

				print "is gen bank format\n"

				sequence = get_the_genbank_lines(read_lines_from_file)

				print "Sequence : ", count_characters(sequence)

				print sequence

			else:
				print "File format not supported, Please retry"