title: parse datetime string with extra characters
body: <p>I have a datetime field with a really silly format:</p>
  
  <p><code>2016423123</code></p>
  
  <p>where <code>2016</code> is the year, <code>4</code> is the month, <code>23</code> is the day, and <code>123</code> is irrelevant.</p>
  
  <p>Does the <code>format</code> parameter of <code>datetime.strptime</code> support directives (like a regex) to ignore characters in the input string?</p>
  
  <p>I know it is possible to just remove the extra characters and then feed the result to the parser, but I have a problem where I have several possible formats (not my invention...), and I was thinking of using try/catch to parse them.</p>