old_contents: #!/usr/bin/env python
  #
  # generates an empty binary file
  # 
  # This tool generates an empty binary file of the required size.
  #
  # Copyright 2018 Espressif Systems (Shanghai) PTE LTD
  #
  # Licensed under the Apache License, Version 2.0 (the "License");
  # you may not use this file except in compliance with the License.
  # You may obtain a copy of the License at
  #
  #     http:#www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing, software
  # distributed under the License is distributed on an "AS IS" BASIS,
  # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  # See the License for the specific language governing permissions and
  # limitations under the License.
  from __future__ import print_function, division
  import argparse
  import os
  import re
  import struct
  import sys
  import hashlib
  import binascii
  
  __version__ = '1.0'
  
  quiet = False
  
  def status(msg):
      """ Print status message to stderr """
      if not quiet:
          critical(msg)
  
  def critical(msg):
      """ Print critical message to stderr """
      if not quiet:
          sys.stderr.write(msg)
          sys.stderr.write('\n')
  
  def generate_blanked_file(size, output_path):
      output = ""
      for i in range(size):
          output += b"\xFF"
      try:
          stdout_binary = sys.stdout.buffer  # Python 3
      except AttributeError:
          stdout_binary = sys.stdout
      with stdout_binary if output_path == '-' else open(output_path, 'wb') as f:
          f.write(output)
  
  def main():
      global quiet
      parser = argparse.ArgumentParser(description='Generates an empty binary file of the required size.')
  
      parser.add_argument('--quiet', '-q', help="Don't print status messages to stderr", action='store_true')
  
      parser.add_argument('--size', help='Size of generated the file',  type=str, required=True)
      
      parser.add_argument('output', help='Path for binary file.', nargs='?', default='-')
      args = parser.parse_args()
  
      quiet = args.quiet
  
      size = int(args.size, 0)
      if size > 0 :
          generate_blanked_file(size, args.output)
      return 0
      
  class InputError(RuntimeError):
      def __init__(self, e):
          super(InputError, self).__init__(e)
  
  if __name__ == '__main__':
      try:
          r = main()
          sys.exit(r)
      except InputError as e:
          print(e, file=sys.stderr)
          sys.exit(2)
  
new_contents: #!/usr/bin/env python
  #
  # generates an empty binary file
  # 
  # This tool generates an empty binary file of the required size.
  #
  # Copyright 2018 Espressif Systems (Shanghai) PTE LTD
  #
  # Licensed under the Apache License, Version 2.0 (the "License");
  # you may not use this file except in compliance with the License.
  # You may obtain a copy of the License at
  #
  #     http:#www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing, software
  # distributed under the License is distributed on an "AS IS" BASIS,
  # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  # See the License for the specific language governing permissions and
  # limitations under the License.
  from __future__ import print_function, division
  from __future__ import unicode_literals
  import argparse
  import os
  import re
  import struct
  import sys
  import hashlib
  import binascii
  
  __version__ = '1.0'
  
  quiet = False
  
  def status(msg):
      """ Print status message to stderr """
      if not quiet:
          critical(msg)
  
  def critical(msg):
      """ Print critical message to stderr """
      if not quiet:
          sys.stderr.write(msg)
          sys.stderr.write('\n')
  
  def generate_blanked_file(size, output_path):
      output = b"\xFF" * size
      try:
          stdout_binary = sys.stdout.buffer  # Python 3
      except AttributeError:
          stdout_binary = sys.stdout
      with stdout_binary if output_path == '-' else open(output_path, 'wb') as f:
          f.write(output)
  
  def main():
      global quiet
      parser = argparse.ArgumentParser(description='Generates an empty binary file of the required size.')
  
      parser.add_argument('--quiet', '-q', help="Don't print status messages to stderr", action='store_true')
  
      parser.add_argument('--size', help='Size of generated the file',  type=str, required=True)
      
      parser.add_argument('output', help='Path for binary file.', nargs='?', default='-')
      args = parser.parse_args()
  
      quiet = args.quiet
  
      size = int(args.size, 0)
      if size > 0 :
          generate_blanked_file(size, args.output)
      return 0
      
  class InputError(RuntimeError):
      def __init__(self, e):
          super(InputError, self).__init__(e)
  
  if __name__ == '__main__':
      try:
          r = main()
          sys.exit(r)
      except InputError as e:
          print(e, file=sys.stderr)
          sys.exit(2)
  
subject: Make gen_empty_partition.py Python 2 & 3 compatible