code: def serial(self, obj: Any, context: Dict):
      data_header, data_buffers = serialize(obj.data)
      idx_header, idx_buffers = serialize(obj.indices)
      indptr_header, indptr_buffers = serialize(obj.indptr)
      header = (
          data_header,  # data_header
          len(data_buffers),  # data_buf_num
          idx_header,  # idx_header
          len(idx_buffers),  # idx_buf_num
          indptr_header,  # indptr_header
          obj.shape,  # shape
      )
      return header, data_buffers + idx_buffers + indptr_buffers, True
  
imports: from typing import Any, Dict, List, Tuple
  import numpy
  from .core import Serializer, buffered, serialize, deserialize
label_desc: Use image node_id 1 for calling the CsrMatrixSerializer obj's underlying member method code with example usage: obj.serial(obj, context) and returns: header,  unknown,  True