code: function createGraphvizOptions(config) {
  	const graphVizOptions = config.graphVizOptions || {};
  
  	return {
  		G: Object.assign({
  			overlap: false,
  			pad: 0.3,
  			rankdir: config.rankdir,
  			layout: config.layout,
  			bgcolor: config.backgroundColor
  		}, graphVizOptions.G),
  		E: Object.assign({
  			color: config.edgeColor
  		}, graphVizOptions.E),
  		N: Object.assign({
  			fontname: config.fontName,
  			fontsize: config.fontSize,
  			color: config.nodeColor,
  			shape: config.nodeShape,
  			style: config.nodeStyle,
  			height: 0,
  			fontcolor: config.nodeColor
  		}, graphVizOptions.N)
  	};
  }
docs: Return options to use with graphviz digraph.
  @param  {Object} config
  @return {Object}