class_docstr: Reader for Mat4 files 
class_docstr_tok: ["Reader","for","Mat4","files"]
code: def guess_byte_order(self):
      self.mat_stream.seek(0)
      mopt = read_dtype(self.mat_stream, np.dtype("i4"))
      self.mat_stream.seek(0)
      if mopt == 0:
          return "<"
      if mopt < 0 or mopt > 5000:
          # Number must have been byteswapped
          return SYS_LITTLE_ENDIAN and ">" or "<"
      # Not byteswapped
      return SYS_LITTLE_ENDIAN and "<" or ">"
  
imports: import sys
  import warnings
  import numpy
  import scipy.sparse
  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 MatFile4Reader obj's underlying member method code with example usage: obj.guess_byte_order() and returns: unknown, str, unknown