code: def bytesio_round_trip(img):
      """Save then load image from bytesio"""
      klass = img.__class__
      bytes_map = bytesio_filemap(klass)
      img.to_file_map(bytes_map)
      return klass.from_file_map(bytes_map)
  
imports: from io import BytesIO
  import numpy
  from ..optpkg import optional_package
  from numpy.testing import assert_array_equal
label_desc: Use image node_id 2 for calling a global function with example usage: bytesio_round_trip(img) and returns: klass