title: showing data in tool tip of a PieChart
body: <p>I'm accessing a GITHUB raw file and using the <code>d3.pie()</code> function making the start and end angles of the pie, at that point the data is showing on console but when I access it in tooltip it gives <code>UNDEFINED</code>.</p>
  
  <p>Do run the code if you can, the link to my github is given where I'm loading my file <code>d3.csv()</code> also FUNCTION TEST is running only once I need to run it till my data runs out.</p>
  
  <pre><code>//CALCULATING RADIUS OF CHART
  var radius = Math.min(width, height) / 2 - margin
  //APPENDING SVG IN DIV HAVING ID pieChart
  var svg = d3.select("#pieChart")
  .append("svg")
  .attr("width", width)
  .attr("height", height)
  .append("g")
  .attr("transform", "translate(" + width / 2 + "," + height / 2 + ")");
  // DATA
  d3.csv 
  ("https://raw.githubusercontent.com/Dehya/django/master/pkpopulation.csv? 
  token=AHXLL23PHQSJGYIYCLA6YX25I7IJA",function(error, data){ 
  // GETTING VALUES AS POPULATION FROM DATA AND CALCULATING THE START AND 
  END 
  ANGLE:
  var pie = d3.pie()
  .value(function(d) {return d.population; })
   console.log(pie(data));
  //SETTING COLOR SCALE
  var color = d3.scaleOrdinal()
      .domain(data)
      .range(["red", "yellow", "green", "blue", "orange"])
  
  function Test(d){ 
      for( i ; i&lt;data.length ; i++)
      {
           console.log(data[i].name + " : " + data[i].population);
           return data[i].name + " : " + data[i].population;
      }
      }
  
  //MAKING TOOPTIP
  var tip = d3.tip()
      .attr("class", "d3-tip")
      .offset([-10, 0])
      .html(Test(data));
    svg.call(tip);
  //MAKING SLICES OF PIE CHART
  svg
      .selectAll("mySlices")
      .data(pie(data))
      .enter()
      .append("path")
          .attr('d',d3.arc()
              .innerRadius(0)
              .outerRadius(radius)
           )
          .attr("fill", function(d){ return color(d.data.key) })
          .attr("stroke","black")
          .style("stroke-width","1px")
          .style("opacity",0.7)
      .on("mouseover", tip.show)
      .on("mouseout", tip.hide);  
  });
  </code></pre>