code: def dumphex(self, data):
      linelength = 16
      hexlinelength = linelength * 2
      chunksize = 8
      for i in range(0, len(data), linelength):
          hexline = hexStr(data[i : i + linelength])
          line = ""
          white = ""
          for j in range(0, hexlinelength, chunksize):
              line = line + white + hexline[j : j + chunksize]
              white = " "
          self._writeraw(line)
          self.newline()
  
imports: from fontTools.misc.textTools import byteord, strjoin, tobytes, tostr
  import sys
  import os
  import string
label_desc: Use image node_id 15 for calling the XMLWriter obj's underlying member method code with example usage: obj.dumphex(data) without return types