How to use the prismjs.util function in prismjs

import Prism from 'prismjs'
import React, { useState, useCallback, useMemo } from 'react'
import { Slate, Editable, withReact } from 'slate-react'
import { Text, createEditor } from 'slate'
import { withHistory } from 'slate-history'
import { css } from 'emotion'

// eslint-disable-next-line
;Prism.languages.markdown=Prism.languages.extend("markup",{}),Prism.languages.insertBefore("markdown","prolog",{blockquote:{pattern:/^>(?:[\t ]*>)*/m,alias:"punctuation"},code:[{pattern:/^(?: {4}|\t).+/m,alias:"keyword"},{pattern:/``.+?``|`[^`\n]+`/,alias:"keyword"}],title:[{pattern:/\w+.*(?:\r?\n|\r)(?:==+|--+)/,alias:"important",inside:{punctuation:/==+$|--+$/}},{pattern:/(^\s*)#+.+/m,lookbehind:!0,alias:"important",inside:{punctuation:/^#+|#+$/}}],hr:{pattern:/(^\s*)([*-])([\t ]*\2){2,}(?=\s*$)/m,lookbehind:!0,alias:"punctuation"},list:{pattern:/(^\s*)(?:[*+-]|\d+\.)(?=[\t ].)/m,lookbehind:!0,alias:"punctuation"},"url-reference":{pattern:/!?\[[^\]]+\]:[\t ]+(?:\S+|<(?:\\.|[^>\\])+>)(?:[\t ]+(?:"(?:\\.|[^"\\])*"|'(?:\\.|[^'\\])*'|\((?:\\.|[^)\\])*\)))?/,inside:{variable:{pattern:/^(!?\[)[^\]]+/,lookbehind:!0},string:/(?:"(?:\\.|[^"\\])*"|'(?:\\.|[^'\\])*'|\((?:\\.|[^)\\])*\))$/,punctuation:/^[\[\]!:]|[<>]/},alias:"url"},bold:{pattern:/(^|[^\\])(\*\*|__)(?:(?:\r?\n|\r)(?!\r?\n|\r)|.)+?\2/,lookbehind:!0,inside:{punctuation:/^\*\*|^__|\*\*$|__$/}},italic:{pattern:/(^|[^\\])([*_])(?:(?:\r?\n|\r)(?!\r?\n|\r)|.)+?\2/,lookbehind:!0,inside:{punctuation:/^[*_]|[*_]$/}},url:{pattern:/!?\[[^\]]+\](?:\([^\s)]+(?:[\t ]+"(?:\\.|[^"\\])*")?\)| ?\[[^\]\n]*\])/,inside:{variable:{pattern:/(!?\[)[^\]]+(?=\]$)/,lookbehind:!0},string:{pattern:/"(?:\\.|[^"\\])*"(?=\)$)/}}}}),Prism.languages.markdown.bold.inside.url=Prism.util.clone(Prism.languages.markdown.url),Prism.languages.markdown.italic.inside.url=Prism.util.clone(Prism.languages.markdown.url),Prism.languages.markdown.bold.inside.italic=Prism.util.clone(Prism.languages.markdown.italic),Prism.languages.markdown.italic.inside.bold=Prism.util.clone(Prism.languages.markdown.bold); // prettier-ignore

const MarkdownPreviewExample = () => {
  const [value, setValue] = useState(initialValue)
  const renderLeaf = useCallback(props => , [])
  const editor = useMemo(() => withHistory(withReact(createEditor())), [])
  const decorate = useCallback(([node, path]) => {
    const ranges = []

    if (!Text.isText(node)) {
      return ranges
    }

    const getLength = token => {
      if (typeof token === 'string') {
        return token.length
      } else if (typeof token.content === 'string') {

(function addJSXSupport() {
  let javascript = Prism.util.clone(Prism.languages.javascript);
  Prism.languages.jsx = Prism.languages.extend('markup', javascript);
  Prism.languages.jsx.tag.pattern = /<\/?[\w.:-]+\s*(?:\s+[\w.:-]+(?:=(?:("|')(\\?[\w\W])*?\1|[^\s'">=]+|(\{[\w\W]*?})))?\s*)*\/?>/i;
  Prism.languages.jsx.tag.inside['attr-value'].pattern = /=[^{](?:('|")[\w\W]*?(\1)|[^\s>]+)/i;
  let jsxExpression = Prism.util.clone(Prism.languages.jsx);
  delete jsxExpression.punctuation;

  jsxExpression = Prism.languages.insertBefore('jsx', 'operator', {
    'punctuation': /=(?={)|[{}[\];(),.:]/
  }, { jsx: jsxExpression });

  Prism.languages.insertBefore('inside', 'attr-value', {
    'script': {
      // Allow for one level of nesting
      pattern: /=(\{(?:\{[^}]*}|[^}])+})/i,
      inside: jsxExpression,
      'alias': 'language-javascript'
    }
  }, Prism.languages.jsx.tag);
})();

return token;
  } else if (typeof token === "string") {
    counter.current++;
    return new Prism.Token(
      "free-text",
      token,
      ["token-" + counter.current, "token-leaf"],
      token
    );
  } else if (Prism.util.type(token.content) === "Array") {
    token.content = addCustomTokens(token.content, counter);
    return token;
  } else {
    counter.current++;
    const aliases =
      Prism.util.type(token.alias) === "Array" ? token.alias : [token.alias];
    aliases.push("token-" + counter.current, "token-leaf");
    token.alias = aliases;
    return token;
  }
}

inside: {
        variable: { pattern: /(!?\[)[^\]]+(?=\]$)/, lookbehind: !0 },
        string: { pattern: /"(?:\\.|[^"\\])*"(?=\)$)/ },
      },
    },
  }),
  (Prism.languages.markdown.bold.inside.url = Prism.util.clone(
    Prism.languages.markdown.url,
  )),
  (Prism.languages.markdown.italic.inside.url = Prism.util.clone(
    Prism.languages.markdown.url,
  )),
  (Prism.languages.markdown.bold.inside.italic = Prism.util.clone(
    Prism.languages.markdown.italic,
  )),
  (Prism.languages.markdown.italic.inside.bold = Prism.util.clone(
    Prism.languages.markdown.bold,
  ));

export default Editor;

Object.entries(Prism.languages).forEach(([name, language]) => {
  if (Prism.util.type(language) === 'Object') {
    insideFences[`language-${name}`] = {
      pattern: new RegExp(`(\`\`\`|~~~)${name}\\W[\\s\\S]*`),
      inside: {
        'cl cl-pre': /(```|~~~).*/,
        rest: language,
      },
    };
  }
});

url: {
    pattern: /!?\[[^\]]+\](?:\([^\s)]+(?:[\t ]+"(?:\\.|[^"\\])*")?\)| ?\[[^\]\n]*\])/,
    inside: {
      variable: {
        pattern: /(!?\[)[^\]]+(?=\]$)/,
        lookbehind: true
      },
      string: {
        pattern: /"(?:\\.|[^"\\])*"(?=\)$)/
      }
    }
  }
});

Prism.languages.markdown.bold.inside.url = Prism.util.clone(Prism.languages.markdown.url);
Prism.languages.markdown.italic.inside.url = Prism.util.clone(Prism.languages.markdown.url);
Prism.languages.markdown.bold.inside.italic = Prism.util.clone(Prism.languages.markdown.italic);
Prism.languages.markdown.italic.inside.bold = Prism.util.clone(Prism.languages.markdown.bold);


/**
 * Define a decorator for markdown styles.
 *
 * @param {Text} text
 * @param {Block} block
 */

function addMarks(characters, tokens, offset) {
  let updatedOffset = offset;
  for (const token of tokens) {
    if (typeof token === 'string') {
      updatedOffset += token.length;

const highlight = code => {
  const grammar = Prism.languages["jsx"];
  const language = null;
  const env = {
    code: code,
    grammar: grammar,
    language: language
  };
  Prism.hooks.run("before-tokenize", env);
  env.tokens = Prism.tokenize(env.code, env.grammar);
  Prism.hooks.run("after-tokenize", env);

  env.tokens = addCustomTokens(env.tokens);

  return Prism.Token.stringify(Prism.util.encode(env.tokens), env.language);
};