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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 list_sections(self):
 """List all sections."""

        if not os.path.exists(self._full_base):
            return []
        return [
            name for name in os.listdir(self._full_base)
            if os.path.isdir(os.path.join(self._full_base, name))
        ]