code: def _interchange_level_from_directory(name):
      # type: (bytes) -> int
      '''
      A function to determine the ISO interchange level from the directory name.
      In theory, there are 3 levels, but in practice we only deal with level 1
      and level 3.
  
      Parameters:
       name - The name to use to determine the interchange level.
      Returns:
       The interchange level determined from this filename.
      '''
      interchange_level = 1
      if len(name) > 8:
          interchange_level = 3
  
      try:
          _check_d1_characters(name)
      except pycdlibexception.PyCdlibInvalidInput:
          interchange_level = 3
  
      return interchange_levef _interchange_level_from_directory(name):
      # type: (bytes) -> int
      '''
      A function to determine the ISO interchange level from the directory name.
      In theory, there are 3 levels, but in practice we only deal with level 1
      and level 3.
  
      Parameters:
       name - The name to use to determine the interchange level.
      Returns:
       The interchange level determined from this filename.
      '''
      interchange_level = 1
      if len(name) > 8:
          interchange_level = 3
  
      try:
          _check_d1_characters(name)
      except pycdlibexception.PyCdlibInvalidInput:
          interchange_level = 3
  
      return interchange_level
docs: A function to determine the ISO interchange level from the directory name.
      In theory, there are 3 levels, but in practice we only deal with level 1
      and level 3.
  
      Parameters:
       name - The name to use to determine the interchange level.
      Returns:
       The interchange level determined from this filename.