old_contents: #!/usr/bin/env python
  # -*- coding: utf-8 -*-
  """
  File: run.py
  Author: huxuan <i(at)huxuan.org>
  Description: Run script for app.
  """
  import os.path
  
  if not os.path.isfile('config.py'):
      raise Exception('Please copy `config.sample.py` to `config.py` with proper'
                      'configuration to make it work.')
  
  from app import app
  
  
  def main():
      """ Main function for run script. """
      app.run()
  
  if __name__ == '__main__':
      main()
  
new_contents: #!/usr/bin/env python
  # -*- coding: utf-8 -*-
  """
  File: run.py
  Author: huxuan <i(at)huxuan.org>
  Description: Run script for app.
  """
  import os.path
  
  if not os.path.isfile('config.py'):
      raise Exception('Please copy `config.sample.py` to `config.py` with proper'
                      ' configuration to make it work.')
  
  from app import app
  
  
  def main():
      """ Main function for run script. """
      app.run()
  
  if __name__ == '__main__':
      main()
  
subject: Add missing space for exception message.