title: Search for a variable string within a string
body: <p>This is the actual problem: I have this text in A1:  </p>
  
  <blockquote>
    <p>The Gross Return of the S&amp;P index over the past year has been 5%. The ISIN for this Gross Return is CH354892. The ISIN for Net Return is CH875621.  </p>
  </blockquote>
  
  <p>I want to write a general function that would return the ISIN for Gross Return, which is <code>CH354892</code>. I was thinking of searching for the words <code>Gross Return</code> and <code>ISIN</code> and if the difference of the positions between them is &lt; 35, I would grab the text starting five positions after <code>Gross Return</code> and ending at eight positions after the start.  </p>
  
  <p>Is there a way to do it?</p>