def __init__(self, names=()):
        """
        Args:
            names(tuple[str]): the names of the tensors to monitor
                on the progress bar.
        """
        super(ProgressBar, self).__init__()
        self._names = [get_op_tensor_name(n)[1] for n in names]
        self._tags = [get_op_tensor_name(n)[0].split("/")[-1] for n in names]
        self._bar = None

        Args:
            names(tuple[str]): the names of the tensors to monitor
                on the progress bar.
        
tensorpack/callbacks/steps.py