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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _write_module_descriptor_file(handle, module_dir):
 """Writes a descriptor file about the directory containing a module. Args: handle: Module name/handle. module_dir: Directory where a module was downloaded. """

  readme = _module_descriptor_file(module_dir)
  readme_content = (
      "Module: %s\nDownload Time: %s\nDownloader Hostname: %s (PID:%d)" %
      (handle, str(datetime.datetime.today()), socket.gethostname(),
       os.getpid()))
  # The descriptor file has no semantic meaning so we allow 'overwrite' since
  # there is a chance that another process might have written the file (and
  # crashed), we just overwrite it.
  tf_utils.atomic_write_string_to_file(readme, readme_content, overwrite=True)