fetchColor = function fetchColor(i) {
            var exp = w.config.stroke.colors;
            var c;
            if (Array.isArray(exp) && exp.length > 0) {
              c = exp[i];
              if (!c) c = '';
              if (typeof c === 'function') {
                return c({
                  value: w.globals.series[i][j],
                  dataPointIndex: j,
                  w: w
                });
              }
            }
            return c;
          }
primary draw method which is called on bar object
@memberof Bar
@param {array} series - user supplied series values
@param {int} seriesIndex - the index by which series will be drawn on the svg
@return {node} element which is supplied to parent chart draw method for appending