code: def write_bytewise(f, source):
      """write one unit at a time"""
      for i in range(0, len(source)):
          f.write(source[i : i + 1])
  
imports: import itertools
  import os
  import platform
  import re
  import sys
  import time
  from optparse import OptionParser
label_desc: Use image node_id 16 for calling a global function with example usage: write_bytewise(f, source) without return types