change some lines from a read file

[utab]

Dear all,

I have to change some lines from a template file, which is rather long
to paste here, but I would like to make some parts of some lines
optional with my command line arguments but I could not see this
directly, I can count the line numbers and decide on this basis to
decide the lines to be configured to my will.

More specifically, say, I have a that file includes

this is an example python file to play around
.
.
.
some lines
.
.
.
. -> an option line for example.
.
.
.
-> another option line so on.

and execute the script
./myScript option1 option2

so that the options at correct locations will be written.

Any other options for this simple job that i can improve my Python a
bit as well.

Best,
Umut