Palindrome

import sys
def substrings(s):
    l = len(s)
    for end in xrange(l, 0, -1):
        for start in xrange(l-end+1):
            yield s[start:start + end]
 
def palindrome(s):
    return s == s[::-1]
 
def longest_palindrome(s):
    for e in substrings(s):
        if palindrome(e):
            return e

s =sys.stdin.readline()
print(longest_palindrome(s))

Test 1

Verdict: RUNTIME ERROR

Traceback (most recent call last):
  File "input/code.py", line 17, in <module>
    print(longest_palindrome(s))
  File "input/code.py", line 12, in longest_palindrome
    for e in substrings(s):
  File "input/code.py", line 4, in substrings
    for end in xrange(l, 0, -1):
NameError: name 'xrange' is not defined

Test 2

Verdict: RUNTIME ERROR

Traceback (most recent call last):
  File "input/code.py", line 17, in <module>
    print(longest_palindrome(s))
  File "input/code.py", line 12, in longest_palindrome
    for e in substrings(s):
  File "input/code.py", line 4, in substrings
    for end in xrange(l, 0, -1):
NameError: name 'xrange' is not defined

Test 3

Verdict: RUNTIME ERROR

Traceback (most recent call last):
  File "input/code.py", line 17, in <module>
    print(longest_palindrome(s))
  File "input/code.py", line 12, in longest_palindrome
    for e in substrings(s):
  File "input/code.py", line 4, in substrings
    for end in xrange(l, 0, -1):
NameError: name 'xrange' is not defined

Test 4

Verdict: RUNTIME ERROR

Traceback (most recent call last):
  File "input/code.py", line 17, in <module>
    print(longest_palindrome(s))
  File "input/code.py", line 12, in longest_palindrome
    for e in substrings(s):
  File "input/code.py", line 4, in substrings
    for end in xrange(l, 0, -1):
NameError: name 'xrange' is not defined

Test 5

Verdict: RUNTIME ERROR

Traceback (most recent call last):
  File "input/code.py", line 17, in <module>
    print(longest_palindrome(s))
  File "input/code.py", line 12, in longest_palindrome
    for e in substrings(s):
  File "input/code.py", line 4, in substrings
    for end in xrange(l, 0, -1):
NameError: name 'xrange' is not defined

Test 6

Verdict: RUNTIME ERROR

Traceback (most recent call last):
  File "input/code.py", line 17, in <module>
    print(longest_palindrome(s))
  File "input/code.py", line 12, in longest_palindrome
    for e in substrings(s):
  File "input/code.py", line 4, in substrings
    for end in xrange(l, 0, -1):
NameError: name 'xrange' is not defined

Test 7

Verdict: RUNTIME ERROR

Traceback (most recent call last):
  File "input/code.py", line 17, in <module>
    print(longest_palindrome(s))
  File "input/code.py", line 12, in longest_palindrome
    for e in substrings(s):
  File "input/code.py", line 4, in substrings
    for end in xrange(l, 0, -1):
NameError: name 'xrange' is not defined