Python - go to two lines above match
<p>In a  text file like this:</p>

<p>First Name last name #<br />
secone name<br />
Address Line 1<br />
Address Line 2<br />
Work Phone: <br />
Home Phone:<br />
Status:<br /></p>

<p>First Name last name #<br />
....same as above...</p>

<p>I need to match string 'Work Phone:' then go two lines up and insert character '|' in the begining of line. so pseudo code would be:</p>

<p>if "Work Phone:" in line:
   go up two lines:
       write | + line
write rest of the lines.</p>

<p>File is about 10 mb and there are about 1000 paragraphs like this. 
Then i need to write it to another file. So desired result would be:</p>

<p>First Name last name #<br />
secone name<br />
|Address Line 1<br />
Address Line 2<br />
Work Phone: <br />
Home Phone:<br />
Status:<br /></p>

<p>thanks for any help.</p>
