code: function handle(msg) {
    // skip if it's an outgoing request (sending input to people to wait for output reply to handle)
    if (msg.input && !msg.output) { return }
    msg = msg || {}
    const hashStr = _.isString(msg) ? msg : msg.hash
    if (hashStr) {
      log.debug('hash string exists for global-client')
      var cb = hashMap[hashStr]
      if (cb) {
        log.debug('hasher.handle invoking cb for global-client')
        delete hashMap[hashStr]
        return cb(msg)
      }
    }
  }
docs: Handler for socket client; use the msg's hash to find a callback function from hashMap, and execute cb(msg) if found.
  Note the payload msg received must contain the same hash, thus it's your job to include the same when replying.
  @param  {JSON} msg The socket client JSON payload.
   /* istanbul ignore next