code: func (p *Profile) SetLabel(key string, value []string) {
  	for _, sample := range p.Sample {
  		if sample.Label == nil {
  			sample.Label = map[string][]string{key: value}
  		} else {
  			sample.Label[key] = value
  		}
  	}
  }
docs: // SetLabel sets the specified key to the specified value for all samples in the
  // profile.