title: How to replace periods after all caps words?
body: <p>I'm working with a textual dataset that requires some cleaning, and I need to replace a specific pattern set. Namely, I need to replace periods with colons following only words of len > 1 which contain only capitalized letters.</p>
  
  <p>I've already tried using regex for this but I can't get it to replace only the period.</p>
  
  <p>Ideally, I'd like to have a function doing the following:</p>
  
  <pre><code>s = "this is a CITATION. AUTHOR, information GOES here AnD. this P. period isn't replaced."
  s = corr(s)
  s = "this is a CITATION: AUTHOR, information GOES here AnD. this P. period isn't replaced."
  </code></pre>
  
  <p>But what I've already tried:</p>
  
  <pre><code>import re
  s = re.sub(r'[A-Z]+\.',':',s)
  </code></pre>
  
  <p>Replaces the occurrence itself with a colon which isn't what I need.</p>