code: func randomLabelPart(c fuzz.Continue, canBeEmpty bool) string {
  	validStartEnd := []charRange{{'0', '9'}, {'a', 'z'}, {'A', 'Z'}}
  	validMiddle := []charRange{{'0', '9'}, {'a', 'z'}, {'A', 'Z'},
  		{'.', '.'}, {'-', '-'}, {'_', '_'}}
  
  	partLen := c.Rand.Intn(64) // len is [0, 63]
  	if !canBeEmpty {
  		partLen = c.Rand.Intn(63) + 1 // len is [1, 63]
  	}
  
  	runes := make([]rune, partLen)
  	if partLen == 0 {
  		return string(runes)
  	}
  
  	runes[0] = validStartEnd[c.Rand.Intn(len(validStartEnd))].choose(c.Rand)
  	for i := range runes[1:] {
  		runes[i+1] = validMiddle[c.Rand.Intn(len(validMiddle))].choose(c.Rand)
  	}
  	runes[len(runes)-1] = validStartEnd[c.Rand.Intn(len(validStartEnd))].choose(c.Rand)
  
  	return string(runes)
  }
docs: // randomLabelPart produces a valid random label value or name-part
  // of a label key.