a point as we need this to draw the
    // line that comes into the chart from the left, but any points prior to that can be removed.
    var removeCount = 0;
    while (this.data.length - removeCount >= maxDataSetLength && this.data[removeCount + 1][0] < oldestValidTime) {
      removeCount++;
    }
    if (removeCount !== 0) {
      this.data.splice(0, removeCount);
    }
  };

  /**
   * Initialises a new <code>SmoothieChart</code>.
   *
   * Options are optional, and should be of the form below. Just sp