docs: function isKeyword(id) {
          if (strict && isStrictModeReservedWord(id)) {
              return true;
          }
  
          // 'const' is specialized as Keyword in V8.
          // 'yield' and 'let' are for compatibility with SpiderMonkey and ES.next.
          // Some others are from future reserved words.
  
          switch (id.length) {
          case 2:
              return (id === 'if') || (id === 'in') || (id === 'do');
          case 3:
              return (id === 'var') || (id === 'for') || (id === 'new') ||
                  (id === 'try') || (id === 'let');
          case 4:
              return (id === 'this') || (id === 'else') || (id === 'case') ||
                  (id === 'void') || (id === 'with') || (id === 'enum');
          case 5:
              return (id === 'while') || (id === 'break') || (id === 'catch') ||
                  (id === 'throw') || (id === 'const') || (id === 'yield') ||
                  (id === 'class') || (id === 'super');
          case 6:
              return (id === 'return') || (id === 'typeof') || (id === 'delete') ||
                  (id === 'switch') || (id === 'export') || (id === 'import');
          case 7:
              return (id === 'default') || (id === 'finally') || (id === 'extends');
          case 8:
              return (id === 'function') || (id === 'continue') || (id === 'debugger');
          case 10:
              return (id === 'instanceof');
          default:
              return false;
          }
      }