class_docstr: A feature concatenation block.
  
  :param in_keys: Keys identifying the input tensors.
  :param out_keys: Keys identifying the output tensors.
  :param in_shapes: List of input shapes.
  :param concat_dim: The index of the concatenation dimension.
code: def __init__(
      self,
      in_keys: Union[str, List[str]],
      out_keys: Union[str, List[str]],
      in_shapes: Union[Sequence[int], List[Sequence[int]]],
      concat_dim: int,
  ):
      super().__init__(
          in_keys=in_keys, out_keys=out_keys, in_shapes=in_shapes
      )
      self.concat_dim = concat_dim
      assert len(self.out_keys) == 1
  
file_path: maze/maze/perception/blocks/general/concat.py
imports: from typing import Union, List, Dict, Sequence
  import torch
  from maze.core.annotations import override
  from maze.perception.blocks.base import PerceptionBlock
label_desc: Use image node_id 1 to create a new ConcatenationBlock object from inherited base classes: PerceptionBlock with example: obj = ConcatenationBlock(in_keys, out_keys, in_shapes, concat_dim)