text: class Line {
  
      constructor(layer, x1, x2, y1, y2) {
  
          this.layer = layer;
          this.x1 = x1;
          this.x2 = x2;
          this.y1 = y1;
          this.y2 = y2;
          this.color = "black";
          this.width = 1;
          this.style = null;
  
      }
  
      setColor(color) {
  
          this.color = color;
      };
  
      setWidth(width) {
          this.width = width;
      };
  
      setStyle(style, value) {
          this.style = [style, value];
      };
  
      draw() {
          return this.layer.append("line")
              .attr("x1", this.x1)
              .attr("x2", this.x2)
              .attr("y1", this.y1)
              .attr("y2", this.y2)
              .attr("stroke", this.color)
              .attr("stroke-width", this.width)
              .style(this.style[0], this.style[1]);
      };
  
  }
  