docs: function (firstEdge, secondEdge) {
  		if (firstEdge === Constants.SOLID && secondEdge === Constants.SOLID) {
  			return Constants.EMPTY;
  		}
  		
  		if (firstEdge === Constants.SOLID && secondEdge === Constants.EMPTY) {
  			return Constants.EMPTY;
  		}
  		
  		return firstEdge;
  	}