setDirection(i) {
    this.direction = i, /.*</.exec(this.direction) && (this.direction = "RL"), /.*\^/.exec(this.direction) && (this.direction = "BT"), /.*>/.exec(this.direction) && (this.direction = "LR"), /.*v/.exec(this.direction) && (this.direction = "TB"), this.direction === "TD" && (this.direction = "TB");
  }
Called by parser when a graph definition is found, stores the direction of the chart.