code: def write_raw_data(arr, hdr, fileobj):
      hdr.set_data_shape(arr.shape)
      hdr.set_data_dtype(arr.dtype)
      fileobj.write(b"\x00" * hdr.get_data_offset())
      fileobj.write(arr.tobytes(order="F"))
  
imports: import contextlib
  import gzip
  import pickle
  from io import BytesIO
  from unittest import mock
  import numpy
  import pytest
  from numpy.testing import assert_array_almost_equal, assert_array_equal
  from packaging.version import Version
  from ..None import __version__
  from ..arrayproxy import ArrayProxy, get_obj_dtype, is_proxy, reshape_dataobj
  from ..deprecator import ExpiredDeprecationError
  from ..nifti1 import Nifti1Header, Nifti1Image
  from ..openers import ImageOpener
  from ..testing import memmap_after_ufunc
  from ..tmpdirs import InTemporaryDirectory
  from .test_fileslice import slicer_samples
  from .test_openers import patch_indexed_gzip
label_desc: Use image node_id 3 for calling a global function with example usage: write_raw_data(arr, hdr, fileobj) without return types