chunk_content: 2_SEQ_LM",
  ...     num_virtual_tokens=20,
  ...     token_dim=768,
  ...     num_transformer_submodules=1,
  ...     num_attention_heads=12,
  ...     num_layers=12,
  ...     encoder_hidden_size=768,
  ... )
  >>> prefix_encoder = PrefixEncoder(config)
  Attributes:
  embedding (torch.nn.Embedding) — The embedding layer of the prefix encoder.
  transform (torch.nn.Sequential) — The two-layer MLP to transform the prefix embeddings if
  prefix_projection is True.
  pre