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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 python_module_name(self) -> str: """ Returns the name of the Python module that this instance refers to, in dotted Python module notation, or a blank string if it doesn't. """

        if not self.is_python:
            return ""
        filepath = self.source_filename_rel_python_root
        dirs_and_base = splitext(filepath)[0]
        dir_and_file_parts = dirs_and_base.split(sep)
        return ".".join(dir_and_file_parts)