Use next item in the list within a condition in a for loop

I have the following loop which is parsing the outputs of a difflib comparison of 2 configuration files and, so far showing me the differences in file 2 (indicated with +) and the heading in the file that the difference falls under e.g. [server]

code:

#!/usr/bin/env python

import difflib
from difflib import Differ

conf = open('C:/Users/fitzs/Documents/Scripts/example_ISAM_conf_file.txt', 'r')
upconf = open('C:/Users/fitzs/Documents/Scripts/Updated_ISAM_conf_file.txt', 'r')

d = difflib.Differ()

diff = list(d.compare(conf.readlines(), upconf.readlines()))# creates a 'generator' list of diffs

delta = ''.join(diff).strip('# ') #converts the list to string


for x in diff:
    x = str(x).strip()
    if x.startswith('+'):
        print(x)
    elif x.startswith('['):
        print(x)

    **Example Output:-**

    The above code is giving me the following example output so far.  

    [server]
    + # web-host-name = www.myhost.com
    + https-port = 1080
    + network-interface = 0.0.0.0
    [process-root-filter]
    [validate-headers]
    [interfaces]
    [header-names]
    [oauth]
    [tfim-cluster:oauth-cluster]
    [session]
    + preserve-inactivity-timeout = 330
    [session-http-headers]

what I'm trying to do is only print a heading (e.g [server] ) if the next element in the list begins with + thereby excluding the headers that have no deltas under them'

on other words for the line with the header to print 2 conditions must be met: 1. the line must begin with [ 2. the next line must begin with +

for example:

[server]
+ # web-host-name = www.myhost.com
+ https-port = 1080
+ network-interface = 0.0.0.0
[session]
+ preserve-inactivity-timeout = 330

To achieve this I've tried changing the above for loop to the following:

for x in range(0, len(diff)):
    stanza = diff[x+1]
    x = str(x).strip()
    if x.startswith('+'):
        print(x)
    elif x.startswith('[') and stanza.startswith('+'):
        print(x)

However, this results in the following error:

Traceback (most recent call last):
  File "C:/Users/fitzs/PycharmProjects/Pydiffer/Pydiffer.py", line 35, in <module>
    stanza = diff[x+1]
IndexError: list index out of range