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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 minify_js(input_files, output_file):
 """ Minifies the input javascript files to the output file. Output file may be same as input to minify in place. In debug mode this function just concatenates the files without minifying. """

    from .modules import minify, utils

    if not isinstance(input_files, (list, tuple)):
        raise RuntimeError('JS minifier takes a list of input files.')

    return {
        'dependencies_fn': utils.no_dependencies,
        'compiler_fn': minify.minify_js,
        'input': input_files,
        'output': output_file,
        'kwargs': {},
    }