failing to print not matched lines from second file

[tester_V]

with open ('file_2','r') as l_few :    f2=l_few.readlines()sp23 = [s.split(',')[3].strip() for s in f2] # collect all the terms you need to comparewith open ('file_1','r') as f1:              for lf1 in f1:        lf1=lf1.strip()        sp1 = lf1.split(",")        if sp1[3] in sp23:            pass # here we have a match so print nothing            # spL2=lf2.split(",")            #print (" File 2 Line matched --> "+lf2)            #break        else :            print (lf1) # print the non-matching line            #break

My bad! the code s actually working!
Thank you very much for your help!

I made some insignificant changes to your code, just easier to read (for me).

with open (file_1,'r') as l_few :
    f1=l_few.readlines()
for s in f1 :
    sp23 = s.split(',')

with open (file_2,'r') as f2:          
    for lf2 in f2:
        lf2=lf2.strip()
        sp2 = lf2.split(",")
        if sp2[3] in sp23:
            pass # here we have a match so print nothing
        else :
            print (lf2) # print the non-matching line
            #break