title: str.startswith using Regex
body: <p>Can i understand why the str.startswith() is not dealing with Regex :</p>
  
  <pre><code>   col1
  0  country
  1  Country
  
  i.e : df.col1.str.startswith('(C|c)ountry')
  </code></pre>
  
  <p>it returns all the values False :</p>
  
  <pre><code>   col1
  0  False
  1  False
  </code></pre>