parameters: (self, node_def, op, message)
docstring: Creates an `UnavailableError`.
docstring_summary: Creates an `UnavailableError`.
docstring_tokens: Creates an UnavailableError .
function: def __init__(self, node_def, op, message):
      """Creates an `UnavailableError`."""
      super(UnavailableError, self).__init__(node_def, op, message,
                                             UNAVAILABLE)
function_tokens: def __init__ ( self , node_def , op , message ) : super ( UnavailableError , self ) . __init__ ( node_def , op , message , UNAVAILABLE )