code: function contentstream (req, debug, inflate) {
    var encoding = (req.headers['content-encoding'] || 'identity').toLowerCase()
    var length = req.headers['content-length']
    var stream
  
    debug('content-encoding "%s"', encoding)
  
    if (inflate === false && encoding !== 'identity') {
      throw createError(415, 'content encoding unsupported')
    }
  
    switch (encoding) {
      case 'deflate':
        stream = zlib.createInflate()
        debug('inflate body')
        req.pipe(stream)
        break
      case 'gzip':
        stream = zlib.createGunzip()
        debug('gunzip body')
        req.pipe(stream)
        break
      case 'identity':
        stream = req
        stream.length = length
        break
      default:
        throw createError(415, 'unsupported content encoding "' + encoding + '"', {
          encoding: encoding
        })
    }
  
    return stream
  }
docs: Get the content stream of the request.
  
  @param {object} req
  @param {function} debug
  @param {boolean} [inflate=true]
  @return {object}
  @api private