class_docstr: Serializer for HDF5 format.
  
  This is the standard serializer in Chainer. The chain hierarchy is simply
  mapped to HDF5 hierarchical groups.
  
  Args:
      group (h5py.Group): The group that this serializer represents.
      compression (int): Gzip compression level.
code: def __getitem__(self, key):
      name = self.group.name + "/" + key
      return HDF5Serializer(
          self.group.require_group(name), self.compression
      )
  
imports: import sys
  import numpy
  import six
  from chainer.backends import _chainerx
  from chainer.backends import _cpu
  from chainer.backends import cuda
  from chainer.backends import intel64
  from chainer import serializer
  import chainerx
label_desc: Use image node_id 2 for calling the HDF5Serializer obj's underlying member method code with example usage: obj.__getitem__(key) and returns: HDF5Serializer