def myApp():
    # read in 2 big old .csv files (in my case tiny)
    path2csv1 = '/home/pedro/myPython/csv/csv1.csv'
    with open(path2csv1) as CSV1:
        list1 = CSV1.readlines()

    path2csv2 = '/home/pedro/myPython/csv/csv2.csv'
    with open(path2csv2) as CSV2:
        list2 = CSV2.readlines()        

    # first problem: the lists are not equal in length?
    if not len(list1) == len(list2):
        print('Problem, the lists are not the same length ... ')
    
    difference = 0   
    if len(list1) > len(list2):
        difference = len(list1) - len(list2)
    if len(list2) > len(list1):
        difference = len(list2) - len(list1)

    dlist = []
    for d in range(0, difference):
        dlist.append('X')

    if len(list1) > len(list2):
        list2 = list2 + dlist
    if len(list2) > len(list1):
        list1 = list1 + dlist   

    # check lengths
    if not len(list1) == len(list2):
        print('Problem, the lists are not the same length ... ')
    elif len(list1) == len(list2):
        print('The lists now have the same length, we can proceed ... '

    # generate a list of tuples of dissimilar lines    
    def getDisimilar_lines():
        for i in range(len(list1)):
            if list1[i] != list2[i]:
                yield (list1[i], list2[i], f'line_{i}')

    not_the_same = getDisimilar_lines()

    for t in not_the_same:
            print(t)    
    # easy to write to Excel from here