class_docstr: RoBERTa encoder.
class_docstr_tok: ["RoBERTa","encoder","."]
code: def build_lm_head(self, embed_dim, output_dim, activation_fn, weight):
      return ModelParallelRobertaLMHead(
          embed_dim, output_dim, activation_fn, weight
      )
  
imports: import logging
  import torch
  import torch.nn
  import torch.nn.functional
  from fairseq import utils
  from fairseq.model_parallel.models.transformer import ModelParallelTransformerEncoder
  from fairseq.models import register_model, register_model_architecture
  from fairseq.models.roberta import roberta_base_architecture, roberta_prenorm_architecture, RobertaEncoder, RobertaModel
  from fairseq.modules import LayerNorm
label_desc: Use image node_id 4 for calling the ModelParallelRobertaEncoder obj's underlying member method code with example usage: obj.build_lm_head(embed_dim, output_dim, activation_fn, weight) and returns: ModelParallelRobertaLMHead