Axis = {
  addAxis: function(svg, axis, xTranslate, yTranslate){
    return svg.append("g")
      .attr("transform", "translate("+xTranslate+", "+yTranslate+")")
      .call(axis);
  },
  addTop: function(svg, scale, xTranslate, yTranslate){
    var axis = d3.axisTop(scale);
    return this.addAxis(svg, axis, xTranslate, yTranslate);
  },
  
  addRight: function(svg, scale, xTranslate, yTranslate){
    var axis = d3.axisRight(scale);
    return this.addAxis(svg, axis, xTranslate, yTranslate);
  },
  
  addBottom: function(svg, scale, xTranslate, yTranslate){
    var axis = d3.axisBottom(scale);
    return this.addAxis(svg, axis, xTranslate, yTranslate);
  },
  
  addLeft: function(svg, scale, xTranslate, yTranslate){
    var axis = d3.axisLeft(scale);
    return this.addAxis(svg, axis, xTranslate, yTranslate);
  }
  
};