def __init__(self,
                 num_units,
                 num_layers,
                 lstm_impl,
                 use_peephole,
                 parameter_init,
                 clip_activation,
                 num_proj,
                 concat=False,
                 name='pblstm_encoder'):

        assert num_proj != 0
        assert num_units % 2 == 0, 'num_unit should be even number.'

        self.num_units = num_units
        self.num_proj = None
        self.num_layers = num_layers
        self.lstm_impl = lstm_impl
        self.use_peephole = use_peephole
        self.parameter_init = parameter_init
        self.clip_activation = clip_activation
        self.name = name