new_contents: import os
  
  from file_generator import FileGenerator
  
  
  class RandomFileGenerator(FileGenerator):
      def __init__(self, directory, prefix='', suffix='', filename_length=10):
          super(RandomFileGenerator, self).__init__(directory=directory,
                                                    prefix=prefix,
                                                    suffix=suffix)
  
      def make_file(self, size, filename=None, filename_length=10, **kwargs):
          super(RandomFileGenerator, self).make_file(size=size,
                                                     filename=filename,
                                                     filename_length=filename_length,
                                                     is_binary=True,
                                                     **kwargs)
  
      def generate_file_content(self, size, **kwargs):
          return os.urandom(size)
  
  
subject: make a random (binary) file generator