Python Insert line before and after string match - python-2.7

Question

I have two variables var1 and var2 on two different line numbers. My task is:
To open an input file, search for the lines beginning with var1 and insert a comment ABOVE the line.
To open the same input file, search for the lines beginning with var2 and insert a comment BELOW the line.
I was able to achieve 1 but not 2.
var1 = 2 #line number
var2 = 5 #line number
comment1 = "inserted text above var1"
comment2 = "inserted text below var2"
some for loop:
found1 = False
found2 = False
for line in fileinput.input(source.txt, inplace=True):
if not found and line.startswith(var1):
print comment1
found1 = True
print line,
if not found and line.startswith(var2):
print line
found1 = True
print comment2,
Input File:
1 abc
2 def
3 ghi
4 jkl
5 mno
6 pqr
7 stu
Output should be :
1 abc
inserted text above var1
2 def
3 ghi
4 jkl
5 mno
inserted text below var2
6 pqr
7 stu

Answer 1

You seem to have a lot of variables that you don't need. The way that I read your code, based on the indenting, you'll always print comment2, and sometimes you'll print the line more then once.
You do not need 2 for loops. You don't ever use found1 or found2, and the variable found is never defined these are variables that you probably don't need. You either need to define source.txt as a variable, or pass it as a string(put " around it, which is what I think you meant to do). var1, and var2 should probably be strings as well, since str.startswith() expects a string to be passed in.
Simplify it a little and I think you wont have a problem. Assuming that you are handling the reading the file correctly, something like this should do the trick.
var1= "2" #line number
var2 = "5" #line number
comment1 = "inserted text above var1"
comment2 = "inserted text below var2"
for line in fileinput.input("source.txt", inplace=True):
if line.startswith(var1):
print comment1
print line
if line.starswith(var2):
print comment2