Conditionally append file contents
<p>I have a source file with contents which needs to be appended to destination file after checking if the all the lines in source file (as a group) are not already there in destination file.</p>

<p>If it's already found in destination file, I should not again append as that would duplicate the contents in the destination file.</p>

<p>This is essentially comparing blocks of lines as a whole.
Is there a way to do this in python without using regex?</p>
