code: function incrmean() {
  	var mu = 0,
  		N = 0,
  		delta;
  	/**
  	* FUNCTION: incrmean( [value] )
  	*	If a `value` is provided, updates and returns the updated mean. If no `value` is provided, returns the current mean.
  	*
  	* @param {Number} [value] - value used to update the mean
  	* @returns {Number} mean value
  	*/
  	return function incrmean( x ) {
  		if ( !arguments.length ) {
  			return mu;
  		}
  		N += 1;
  		delta = x - mu;
  		mu += delta / N;
  		return mu;
  	};
  }
docs: INCREMENTAL MEAN // 
  FUNCTION: incrmean()
  Returns a method to compute an arithmetic mean incrementally.
  
  @returns {Function} method to compute an arithmetic mean incrementally