code: def _set_content_type(kwargs):
      
      if 'files' in kwargs:
          return  # requests will automatically set the content-type
      headers = kwargs.pop('headers', {})
      headers.setdefault('content-type', 'application/json')
      kwargs['headers'] = headers
docs: If the 'content-type' header is unset, set it to 'applcation/json'.
  
      The 'content-type' will not be set if doing a file upload as requests will
      automatically set it.
  
      :param kwargs: A ``dict``. The keyword args supplied to :func:`request` or
          one of the convenience functions like it.
      :return: Nothing. ``kwargs`` is modified in-place.