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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 create_manifest(self):
 """Construct the list of files to be tracked by the runlog."""

        config_path = os.path.join(self.expt.control_path,
                                   DEFAULT_CONFIG_FNAME)

        self.manifest = []

        if os.path.isfile(config_path):
            self.manifest.append(config_path)

        for model in self.expt.models:
            config_files = model.config_files + model.optional_config_files

            self.manifest.extend(os.path.join(model.control_path, f)
                                 for f in config_files)

        # Add file manifests to runlog manifest
        for mf in self.expt.manifest:
            self.manifest.append(mf.path)