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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 _root_path(self):
 """ROOT_PATH_FOR_DYNACONF or the path of first loaded file or '.'"""

        if self.ROOT_PATH_FOR_DYNACONF is not None:
            return self.ROOT_PATH_FOR_DYNACONF
        elif self._loaded_files:  # called once
            root_path = os.path.dirname(self._loaded_files[0])
            self.set("ROOT_PATH_FOR_DYNACONF", root_path)
            return root_path