code: func sampleFormat(p *profile.Profile, f *flags) (sampleValueFunc, string, string) {
  	valueIndex := *f.flagSampleIndex
  
  	if *f.flagMean {
  		return meanExtractor(valueIndex), "mean_" + p.SampleType[valueIndex].Type, p.SampleType[valueIndex].Unit
  	}
  
  	return valueExtractor(valueIndex), p.SampleType[valueIndex].Type, p.SampleType[valueIndex].Unit
  }
docs: // sampleFormat returns a function to extract values out of a profile.Sample,
  // and the type/units of those values.