 .attr('transform', `rotate(-90)`)
            .attr('x', -innerHeight / 2)
            .attr('y', -80)
            .attr('fill', 'white')
            .text(yAxisLabel)
            .attr('text-anchor', 'middle') // Make label at the middle of axis. 
            yAxisGroup.selectAll('.domain').remove(); // we can select multiple tags using comma to seperate them and we can use space to signify nesting; 
            
            let xAxisGroup = g.append('g').call(xAxis).attr('transform', `translate(${0}, ${i