class_docstr: Metadata describing serialized sample in a memory buffer.
  
  It is passed through memory, stored after sample it describes.
code: def from_np(cls, offset, np_array):
      return cls(
          offset, np_array.shape, np_array.dtype, np_array.nbytes
      )
  
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 SampleMeta obj's underlying member method code with example usage: obj.from_np(cls, offset, np_array) and returns: cls