old_contents: #!/usr/bin/env python
  import os
  import subprocess
  import sys
  
  
  def main(argv=None):
      if argv is None or len(argv) == 0 or len(argv) > 2:
          print("Usage: databaker_process.py <notebook_file> <input_file>")
          print()
          print("<input_file> is optional; it replaces DATABAKER_INPUT_FILE")
          print("in the notebook.")
          print("The input file should also be in the same directory as the")
          print("notebook.")
          sys.exit(1)
  
      process_env = os.environ.copy()
  
      if len(argv) == 2:
          process_env['DATABAKER_INPUT_FILE'] = argv[1]
  
      # TODO get custom templates working; according to this:
      # https://github.com/jupyter/nbconvert/issues/391
      # they should work, but I get TemplateNotFound when using absolute path
      # for template.
      cmd_line = ['jupyter', 'nbconvert', '--to', 'html', '--execute', argv[0]]
      print("Running:", ' '.join(cmd_line))
      subprocess.call(args=cmd_line, env=process_env)
  
  
  if __name__ == '__main__':
      main(sys.argv[1:])
  
new_contents: #!/usr/bin/env python
  import os
  import subprocess
  import sys
  
  
  def main(argv=sys.argv[1:]):
      if argv is None or len(argv) == 0 or len(argv) > 2:
          print("Usage: databaker_process.py <notebook_file> <input_file>")
          print()
          print("<input_file> is optional; it replaces DATABAKER_INPUT_FILE")
          print("in the notebook.")
          print("The input file should also be in the same directory as the")
          print("notebook.")
          sys.exit(1)
  
      process_env = os.environ.copy()
  
      if len(argv) == 2:
          process_env['DATABAKER_INPUT_FILE'] = argv[1]
  
      # TODO get custom templates working; according to this:
      # https://github.com/jupyter/nbconvert/issues/391
      # they should work, but I get TemplateNotFound when using absolute path
      # for template.
      cmd_line = ['jupyter', 'nbconvert', '--to', 'html', '--execute', argv[0]]
      print("Running:", ' '.join(cmd_line))
      subprocess.call(args=cmd_line, env=process_env)
  
  
  if __name__ == '__main__':
      main()
  
subject: Fix argument passing