Change three little circles

gistfile1.js

//On the page http://bost.ocks.org/mike/circles/
//This will change the first set of circles as an example of 
//how all of that works.  Paste this into your chrome console 
//when on that page and then execute changeFirstCircles([4, 4, 4])
//or any other numbers you want.
var chanageFirstCircles = function(newDataSet)
{
    
    // Generic function that binds the data
    var f = function(d) { return d; }

    // Get the first svg
    var svg = d3.select('svg');

    // Add the data
    var circles = svg.selectAll('circle').data(newDataSet);

    // Change the existing data  
    circles.attr('r', f).attr('cx', f).attr('cy', f);

    // Add the new data
    circles.enter().append('circle').attr('r', f).attr('cx', f).attr('cy', f);

    // Remove the old data
    circles.exit().remove();
}