code: func (c *PCPClient) MustRegisterString(str string, val interface{}, t MetricType, s MetricSemantics, u MetricUnit) Metric {
  	if m, err := c.RegisterString(str, val, t, s, u); err != nil {
  		panic(err)
  	} else {
  		return m
  	}
  }
docs: // MustRegisterString is simply a RegisterString that panics