old_contents: var fs = require("fs");
  var path = require("path");
  
  var user_data_path = path.join(process.env["HOME"], ".spoor.json");
  
  module.exports = {
    "read_user_data": function(cb) {
      fs.readFile(user_data_path, function(err, data) {
        cb(err, data);
      });
    },
  
    "write_user_data": function(user_data, cb) {
      fs.writeFile(user_data_path, JSON.stringify(user_data), function(err) {
        cb(err);
      });
    }
  };
  
new_contents: var fs = require("fs");
  var path = require("path");
  
  var user_data_path = path.join(process.env["HOME"], ".spoor.json");
  
  module.exports.read_user_data = function(cb) {
    fs.readFile(user_data_path, function(err, data) {
      cb(err, data);
    });
  };
  
  module.exports.write_user_data = function(user_data, cb) {
    fs.writeFile(user_data_path, JSON.stringify(user_data), function(err) {
      cb(err);
    });
  };
  
subject: refactor utilities