title: cant replace more than 1 underscore with a single underscore in the string(regex python)
body: <pre><code>def strip_string(s):
      import re
      replaced_string = re.sub('[^\\w/]+', '_', s)
      return replaced_string
  print(strip_string('h^&amp;ell`.,  |o w/p]{+p__orld'))
  </code></pre>