function drawGridLines() {
            svg.select('.grid-lines-group')
                .selectAll('line')
                .remove();

            if (grid === 'horizontal' || grid === 'full') {
                drawHorizontalGridLines();
            }

            if (grid === 'vertical' || grid === 'full') {
                drawVerticalGridLines();
            }

            drawHorizontalExtendedLine();
        }
Draws grid lines on the background of the chart
@return {void}
@private