title: Check if a filename is valid
body: <p>What would be the most conservative way to check if a file-name is valid in Python on all platforms (including mobile platforms like Android, iOS)? </p>
  
  <p>Ex. </p>
  
  <p>this_is_valid_name.jpg -> Valid</p>
  
  <p>**adad.jpg -> Invalid</p>
  
  <p>a/ad -> Invalid</p>