code: func NewCumulativeDistribution(name string, description string, metadata *types.MetricMetadata, bucketer *distribution.Bucketer, fields ...field.Field) CumulativeDistribution {
  	if metadata == nil {
  		metadata = &types.MetricMetadata{}
  	}
  	m := &cumulativeDistributionMetric{
  		nonCumulativeDistributionMetric{
  			metric: metric{
  				MetricInfo: types.MetricInfo{
  					Name:        name,
  					Description: description,
  					Fields:      fields,
  					ValueType:   types.CumulativeDistributionType,
  				},
  				MetricMetadata: *metadata,
  			},
  			bucketer: bucketer,
  		},
  	}
  	registry.Add(m)
  	return m
  }
docs: // NewCumulativeDistribution returns a new cumulative-distribution-valued
  // metric.