code: def _try_to_get_extension(obj):
      
      if is_path(obj):
          path = obj
  
      elif is_path_obj(obj):
          return obj.suffix[1:]
  
      elif is_file_stream(obj):
          try:
              path = get_path_from_stream(obj)
          except ValueError:
              return None
  
      elif is_ioinfo(obj):
          path = obj.path
  
      else:
          return None
  
      if path:
          return get_file_extension(path)
  
      return None
docs: Try to get file extension from given path or file object.
  
      :param obj: a file, file-like object or something
      :return: File extension or None
  
      >>> _try_to_get_extension("a.py")
      'py'