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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 add_size_info (self):
 """Get size of file content and modification time from filename path."""

        if self.is_directory():
            # Directory size always differs from the customer index.html
            # that is generated. So return without calculating any size.
            return
        filename = self.get_os_filename()
        self.size = fileutil.get_size(filename)
        self.modified = datetime.utcfromtimestamp(fileutil.get_mtime(filename))