src/transformers/models/mpnet/modeling_mpnet.py/MPNetAttention/__init__
class MPNetAttention:    def __init__(self, config):
        super().__init__()
        self.attn = MPNetSelfAttention(config)
        self.LayerNorm = nn.LayerNorm(config.hidden_size, eps=config.layer_norm_eps)
        self.dropout = nn.Dropout(config.hidden_dropout_prob)

        self.pruned_heads = set()