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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 run_script(self, script_name, script_args=None, node_paths=None):
 """Returns a command to execute a package.json script. :param script_name: Name of the script to name. Note that script name 'test' can be used to run node tests. :param script_args: Args to be passed to package.json script. :param node_paths: A list of path that should be included in $PATH when running the script. """

    # TODO: consider add a pants.util function to manipulate command line.
    package_manager_args = self._get_run_script_args()
    package_manager_args.append(script_name)
    if script_args:
      package_manager_args.append('--')
      package_manager_args.extend(script_args)
    return self.run_command(args=package_manager_args, node_paths=node_paths)