class_docstr: Gather the input from sequence parallel region and concatenate.
code: def forward(ctx, input_, to_model_parallel: bool = True):
      ctx.to_model_parallel = to_model_parallel
      return _gather_along_first_dim(input_)
  
imports: import torch
  from apex.transformer.parallel_state import get_tensor_model_parallel_group
  from apex.transformer.parallel_state import get_tensor_model_parallel_world_size
  from apex.transformer.parallel_state import get_tensor_model_parallel_rank
  from apex.transformer.tensor_parallel.utils import split_tensor_along_last_dim
label_desc: Use image node_id 2 for calling the _GatherFromSequenceParallelRegion obj's underlying member method code with example usage: obj.forward(ctx, input_, to_model_parallel) and returns: _gather_along_first_dim