class_docstr: For buffers, report the number of bytes.
code: def __call__(self, x):
      if x is not None:
          return "%d bytes" % len(x)
      else:
          return "--"
  
imports: import json
  import os
  import re
  import sys
  import numpy
label_desc: Use image node_id 1 for calling the DataSizeMapper obj's underlying member method code with example usage: obj.__call__(x) and returns: unknown, str