code: def buffer(self, size):
      return ctypes.cast(
          self.memory.ptr, ctypes.POINTER(ctypes.c_ubyte * size)
      ).contents
  
imports: import ctypes
  import mpi4py.MPI
  import numpy
  from chainermn.communicators import _communication_utility
  import chainer.backends
  import chainerx
label_desc: Use image node_id 4 for calling the HostPinnedMemory obj's underlying member method code with example usage: obj.buffer(size) and returns: ctypes