use the `prism-tomorrow.css` theme file, just
           * set `theme` to 'tomorrow'.
           *
           * @attribute theme
           * @type string
           * @default ''
           */
          theme: {
            type: String,
            value: ''
          },
          /**
           * The `inputValue` attribute allows you to manually pass a string
           * to be used as the code source for the element. Changes to the
           * `inputValue` cause the element to be re-highlighted. This i