code: function drawHorizontalGridLines() {
              maskGridLines = svg.select('.grid-lines-group')
                  .selectAll('line.horizontal-grid-line')
                  .data(yScale.ticks(yTicks))
                  .enter()
                    .append('line')
                      .attr('class', 'horizontal-grid-line')
                      .attr('x1', xAxisPadding.left)
                      .attr('x2', chartWidth)
                      .attr('y1', (d) => yScale(d))
                      .attr('y2', (d) => yScale(d));
          }
docs: Draw horizontal gridles of the chart
  These gridlines are parallel to x-axis
  @return {void}
  @private