text: var smash = require("smash"),
    d3 = require('d3');
  
  module.exports = function () {
    var files = [].slice.call(arguments).map(function (d) {
        return "src/" + d;
      }),
      expression = "vg",
      sandbox = { 'd3': d3 };
  
    files.unshift("src/core/_start");
    files.push("src/core/_end");
  
    function topic() {
      smash.load(files, expression, sandbox, this.callback);
    }
  
    topic.expression = function (_) {
      expression = _;
      return topic;
    };
  
    return topic;
  };
  
  process.on("uncaughtException", function (e) {
    console.trace(e.stack);
  });