code: function funcWithReturnFromSnippet(js) {
      // auto-"return"
      if (js.indexOf('return') === -1) {
          if (js.substring(js.length - 1) === ';') {
              js = js.substring(0, js.length - 1);
          }
          js = 'return (' + js + ')';
      }
  
      // Expose level definitions to condition func context
      var varDefs = [];
      Object.keys(upperNameFromLevel).forEach(function (lvl) {
          varDefs.push(format('var %s = %d;',
                  upperNameFromLevel[lvl], lvl));
      });
      varDefs = varDefs.join('\n') + '\n';
  
      return (new Function(varDefs + js));
  }
docs: Return a function for the given JS code that returns.
  
  If no 'return' in the given javascript snippet, then assume we are a single
  statement and wrap in 'return (...)'. This is for convenience for short
  '-c ...' snippets.