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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 _validate_tools(self, tool):
 """ Use tool_supported or tool """


        tools = []
        if not tool:
            if len(self.project['common']['tools_supported']) == 0:
                logger.info("No tool defined.")
                return -1
            tools = self.project['common']['tools_supported']
        else:
            tools = [tool]
        return tools