| 123456789101112131415161718192021222324252627282930 | module.exports = parseArgumentsfunction isWritable(stream) {    return typeof stream.write === "function" &&        typeof stream.end === "function"}function parseArguments(req, res, opts, callback) {    // (req, cb)    if (typeof res === "function") {        callback = res        opts = {}        res = null    }    // (req, res, cb)    if (typeof opts === "function") {        callback = opts        opts = {}    }    // (req, opts, cb)    if (res && !isWritable(res)) {        opts = res        res = null    }    // default (req, res, opts, cb)    return { req: req, res: res, opts: opts, callback: callback }}
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