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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 execute_builder(self, entry_point, toolchain, spec):
 """ Accepts the arguments provided by the builder and executes them. """


        toolchain(spec)
        if not exists(spec['export_target']):
            logger.error(
                "the entry point '%s' from package '%s' failed to "
                "generate an artifact at '%s'",
                entry_point, entry_point.dist, spec['export_target']
            )
            return {}
        return self.generate_metadata_entry(entry_point, toolchain, spec)