code: def post(self, filepath):
          
          try:
              content = self.get_body_argument('content')
              self.fs.write_file(filepath, content)
              self.write({'msg': 'Updated file at {}'.format(filepath)})
          except OSError:
              raise tornado.web.HTTPError(404)
docs: Write the given contents to the specified file. This is not
          an append, all file contents will be replaced by the contents
          given.