code: function interpretEscapes(str) {
      var escapes = {
          b: '\b',
          f: '\f',
          n: '\n',
          r: '\r',
          t: '\t'
      };
      return str.replace(/\\(u[0-9a-fA-F]{4}|[^u])/, function (_, escape) {
          var type = escape.charAt(0);
          var hex = escape.slice(1);
          if (type === 'u') {
              return String.fromCharCode(parseInt(hex, 16));
          }
          if (escapes.hasOwnProperty(type)) {
              return escapes[type];
          }
          return type;
      });
  }
docs: Turn escaped characters into real ones (e.g. '\\n' becomes '\n').