code: function(index, pathString, x, y, colour) {
      if (this.options.highlight_colours && this.options.highlight_colours.hasOwnProperty(index)) {
        colour = this.options.highlight_colours[index];
      }
  
      x = x + this.bar_padding;
      pathString += 'M' + x + ',' + this.start_y;
      pathString += 'L' + x + ',' + y;
      this.paper.path(pathString).attr({ stroke: colour, 'stroke-width': this.bar_width + 'px' });
      pathString = '';
      x = x + this.step;
      pathString += 'M' + x + ',' + this.start_y;
      return pathString;
    }
docs: Generates paths for Raphael.
  
  @param {Integer} index The index of the data value to plot
  @param {String} pathString The pathString so far
  @param {Integer} x The x-coord to plot
  @param {Integer} y The y-coord to plot
  @param {String} colour A string that represents a colour
  @returns {String} The resulting path string