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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 _detect(self):
 """ Detect high level calls which return a value that are never used """

        results = []
        for c in self.slither.contracts:
            for f in c.functions + c.modifiers:
                if f.contract != c:
                    continue
                unused_return = self.detect_unused_return_values(f)
                if unused_return:
                    info = "{}.{} ({}) does not use the value returned by external calls:\n"
                    info = info.format(f.contract.name,
                                       f.name,
                                       f.source_mapping_str)
                    for node in unused_return:
                        info += "\t-{} ({})\n".format(node.expression, node.source_mapping_str)

                    json = self.generate_json_result(info)
                    self.add_function_to_json(f, json)
                    self.add_nodes_to_json(unused_return, json)
                    results.append(json)

        return results