code: function Datum() {
  	if ( !( this instanceof Datum ) ) {
  		return new Datum();
  	}
  	// Metric (required):
  	this._metric = null;
  
  	// Timestamp (required):
  	this._timestamp = null;
  
  	// Value (required):
  	this._value = null;
  
  	// Tags (optional):
  	this._tags = {};
  
  	return this;
  }
docs: DATUM // 
  FUNCTION: Datum()
  OpenTSDB datum contructor.
  
  @constructor
  @returns {Datum} Datum instance