setStatus (field, val) {
    if (arguments.length === 2) {
      if (!this.status) {
        this.status = {}
      }
      this.status[field] = val
    } else {
      const md = field instanceof grpc.Metadata ? field.getMap() : field

      if (typeof md === 'object') {
        for (const key in md) {
          this.setStatus(key, md[key])
        }
      }
    }
  }
Sets specific response status / trailer metadata field value
@param {String|Object} field the metadata field name or object for metadata
@param {*} val the value of the field
@example <caption>Using string field name and value</caption>
ctx.response.setStatus('foo', 'bar')
@example <caption>Using object</caption>
ctx.response.setStatus({
  foo: 'bar'
})