code: def set_ctype(self, ctype, orig_ctype=None):
          
  
          if self.ctype is None:
              self.ctype = ctype
              self.orig_ctype = orig_ctype
docs: Set the selected content type.  Will not override the value of
          the content type if that has already been determined.
  
          :param ctype: The content type string to set.
  
          :param orig_ctype: The original content type, as found in the
                             configuration.