code: function(callback) {
  		"use strict";
  
  		this.root.transition().duration(this.options.animationDuration)
  			.attr("width", 0)
  			.attr("height", 0)
  			.remove()
  			.each("end", function() {
  				if (typeof callback === "function") {
  					callback();
  				} else if (typeof callback !== "undefined") {
  					console.log("Provided callback for destroy() is not a function.");
  				}
  			})
  		;
  
  		return null;
  	}
docs: Destroy the calendar
  
  Usage: cal = cal.destroy();
  
  @since  3.3.6
  @param function A callback function to trigger after destroying the calendar
  @return null