setupDebugTip () {
    // debug in a running dev process.
    process.stdin
    && process.stdin.on('data', chunk => {
      const parsed = chunk.toString('utf-8').trim()
      if (parsed === '*') {
        console.log(Object.keys(this.context))
      }
      if (this.context[parsed]) {
        console.log(this.context[parsed])
      }
    })
  }
Set up a shortcut to debug context under dev.