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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 _GetParentModificationTime(self, gzip_file_entry):
 """Retrieves the modification time of the file entry's parent file. Note that this retrieves the time from the file entry of the parent of the gzip file entry's path spec, which is different from trying to retrieve it from the gzip file entry's parent file entry. It would be preferable to retrieve the modification time from the metadata in the gzip file itself, but it appears to not be set when the file is written by fseventsd. Args: gzip_file_entry (dfvfs.FileEntry):
 file entry of the gzip file containing the fseventsd data. Returns: dfdatetime.DateTimeValues: parent modification time, or None if not available. """

    parent_file_entry = path_spec_resolver.Resolver.OpenFileEntry(
        gzip_file_entry.path_spec.parent)
    if not parent_file_entry:
      return None

    return parent_file_entry.modification_time