class GPT2Model(nn.Module):

def __init__(self, config):
        super(GPT2Model, self).__init__(config)

        self.wte = nn.Embedding(config.vocab_size, config.n_embd)
        self.wpe = nn.Embedding(config.n_positions, config.n_embd)

        self.drop = nn.Dropout(config.embd_pdrop)
        self.h = nn.ModuleList([Block(config.n_ctx, config, scale=True) for _ in range(config.n_layer)])
        self.ln_f = LayerNorm(config.n_embd, eps=config.layer_norm_epsilon)

        self.apply(self.init_weights)

    def init_weights(self):
        raise NotImplementedError

    def forward(self, input_ids, past=None):
        raise NotImplementedError