title: Python search files with multiple extensions
body: <p>I wish to search a directory, and all contained subdirectories, for files with a substring contained within their name and one of three possible extensions</p>
  
  <p>Please can you help me edit the following code</p>
  
  <pre><code>os.chdir(directory)
  files = glob.glob("**/*{}*.pro".format(myStr), recursive = True)
  </code></pre>
  
  <p>I wish to find files with the extension .pro, .bd3 and .mysql</p>
  
  <p>I'm running Python 3.5</p>