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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 layout_json_schema(self):
 """Load layout.json schema file."""

        if self._layout_json_schema is None and self.layout_json_schema_file is not None:
            if os.path.isfile(self.layout_json_schema_file):
                with open(self.layout_json_schema_file) as fh:
                    self._layout_json_schema = json.load(fh)
        return self._layout_json_schema