code: def read(self, sources):
          
  
          all_read = True
  
          if not isinstance(sources, list):
              sources = [sources]
  
          if self._sources_read:
              for source in sources:
                  all_read &= self._read(source)
          else:
              for i, source in enumerate(sources):
                  if isinstance(source, IOBase):
                      sources[i] = source.read()
              self._sources.extend(sources)
  
          return all_read
docs: Queues the config sources to be read later (when config is accessed), or reads immediately if config has already
          been accessed.
  
          :param file/str/list sources: Config source string, file name, or file pointer, or list of the other sources.
                                        If file source does not exist, it is ignored.
          :return: True if all sources were successfully read or will be read, otherwise False