class_docstr: Describes offset within shared memory chunk and size of serialized list of
  `SampleMeta` instances
code: def from_writer(cls, writer):
      return cls(writer.data_size, writer.meta_data_size)
  
imports: import os
  from nvidia.dali._multiproc import shared_mem
  from nvidia.dali._multiproc.messages import ShmMessageDesc
  from nvidia.dali._utils.external_source_impl import assert_cpu_sample_data_type, sample_to_numpy
  import pickle
label_desc: Use image node_id 2 for calling the SharedBatchMeta obj's underlying member method code with example usage: obj.from_writer(cls, writer) and returns: cls