what is this i don't even

greplin1.py

text = open('gettysburg.txt','r').read()
for x in reversed(range(len(text))):
    print "Now on length " + str(x)
    done = False
    substring = text[0:x]
    for i in range((len(text) + 1) - x):
        print "Now on position " + str(i)
        if x+i <= len(text):
            substring = text[0+i:x+i]
            if substring == substring[::-1]:
                print substring
                done = True
                break
        else:
            pass
    if done: break
    else: pass