code: def write_bytes(self, arr):
      self.file_stream.write(arr.tostring(order="F"))
  
imports: from __future__ import division, print_function, absolute_import
  import sys
  import warnings
  import numpy
  from numpy.compat import asbytes, asstr
  import scipy.sparse
  from scipy._lib.six import string_types
  from .miobase import MatFileReader, docfiller, matdims, read_dtype, convert_dtypes, arr_to_chars, arr_dtype_number
  from .mio_utils import squeeze_element, chars_to_strings
  from functools import reduce
label_desc: Use image node_id 2 for calling the VarWriter4 obj's underlying member method code with example usage: obj.write_bytes(arr) without return types