Emphasis and stress, you guys!
\n```\n\n\n\n\n\n###### Transforming between ecosystems\n\nEcosystems can be combined in two modes.\n\n**Bridge** mode transforms the tree from one format (*origin*) to another\n(*destination*).\nA different processor runs on the destination tree.\nAfterwards, the original processor continues with the origin tree.\n\n**Mutate** mode also transforms the syntax tree from one format to another.\nBut the original processor continues transforming the destination tree.\n\nIn the previous example (βProgramming interfaceβ), `remark-retext` is used in\nbridge mode: the origin syntax tree is kept after retext is done; whereas\n`remark-rehype` is used in mutate mode: it sets a new syntax tree and discards\nthe origin tree.\n\nThe following plugins lets you combine ecosystems:\n\n* [`remark-retext`][remark-retext] β turn markdown into natural language\n* [`remark-rehype`][remark-rehype] β turn markdown into HTML\n* [`rehype-retext`][rehype-retext] β turn HTML into natural language\n* [`rehype-remark`][rehype-remark] β turn HTML into markdown\n\n## API\n\nThis package exports the identifier `unified` (the root `processor`).\nThere is no default export.\n\n### `processor()`\n\nCreate a new processor.\n\n###### Returns\n\nNew *[unfrozen][api-freeze]* processor ([`processor`][api-processor]).\n\nThis processor is configured to work the same as its ancestor.\nWhen the descendant processor is configured in the future it does not affect\nthe ancestral processor.\n\n###### Example\n\nThis example shows how a new processor can be created (from `remark`) and linked\nto **stdin**(4) and **stdout**(4).\n\n```js\nimport process from 'node:process'\nimport concatStream from 'concat-stream'\nimport {remark} from 'remark'\n\nprocess.stdin.pipe(\n concatStream(function (buf) {\n process.stdout.write(String(remark().processSync(buf)))\n })\n)\n```\n\n### `processor.compiler`\n\nCompiler to use ([`Compiler`][api-compiler], optional).\n\n### `processor.data([key[, value]])`\n\nConfigure the processor with info available to all plugins.\nInformation is stored in an object.\n\nTypically, options can be given to a specific plugin, but sometimes it makes\nsense to have information shared with several plugins.\nFor example, a list of HTML elements that are self-closing, which is needed\nduring all [phases][overview].\n\n> π **Note**: setting information cannot occur on *[frozen][api-freeze]*\n> processors.\n> Call the processor first to create a new unfrozen processor.\n\n> π **Note**: to register custom data in TypeScript, augment the\n> [`Data`][api-data] interface.\n\n###### Signatures\n\n* `processor = processor.data(key, value)`\n* `processor = processor.data(dataset)`\n* `value = processor.data(key)`\n* `dataset = processor.data()`\n\n###### Parameters\n\n* `key` ([`keyof Data`][api-data], optional) β field to get\n* `value` ([`Data[key]`][api-data]) β value to set\n* `values` ([`Data`][api-data]) β values to set\n\n###### Returns\n\nThe current processor when setting ([`processor`][api-processor]), the value at\n`key` when getting ([`Data[key]`][api-data]), or the entire dataset when\ngetting without key ([`Data`][api-data]).\n\n###### Example\n\nThis example show how to get and set info:\n\n```js\nimport {unified} from 'unified'\n\nconst processor = unified().data('alpha', 'bravo')\n\nprocessor.data('alpha') // => 'bravo'\n\nprocessor.data() // => {alpha: 'bravo'}\n\nprocessor.data({charlie: 'delta'})\n\nprocessor.data() // => {charlie: 'delta'}\n```\n\n### `processor.freeze()`\n\nFreeze a processor.\n\nFrozen processors are meant to be extended and not to be configured directly.\n\nWhen a processor is frozen it cannot be unfrozen.\nNew processors working the same way can be created by calling the processor.\n\nItβs possible to freeze processors explicitly by calling `.freeze()`.\nProcessors freeze automatically when `.parse()`, `.run()`, `.runSync()`,\n`.stringify()`, `.process()`, or `.processSync()` are called.\n\n###### Returns\n\nThe current processor ([`processor`][api-processor]).\n\n###### Example\n\nThis example, `index.js`, shows how `rehype` prevents extensions to itself:\n\n```js\nimport rehypeParse from 'rehype-parse'\nimport rehypeStringify from 'rehype-stringify'\nimport {unified} from 'unified'\n\nexport const rehype = unified().use(rehypeParse).use(rehypeStringify).freeze()\n```\n\nThat processor can be used and configured like so:\n\n```js\nimport {rehype} from 'rehype'\nimport rehypeFormat from 'rehype-format'\n// β¦\n\nrehype()\n .use(rehypeFormat)\n // β¦\n```\n\nA similar looking example is broken as operates on the frozen interface.\nIf this behavior was allowed it would result in unexpected behavior so an error\nis thrown.\n**This is not valid**:\n\n```js\nimport {rehype} from 'rehype'\nimport rehypeFormat from 'rehype-format'\n// β¦\n\nrehype\n .use(rehypeFormat)\n // β¦\n```\n\nYields:\n\n```txt\n~/node_modules/unified/index.js:426\n throw new Error(\n ^\n\nError: Cannot call `use` on a frozen processor.\nCreate a new processor first, by calling it: use `processor()` instead of `processor`.\n at assertUnfrozen (~/node_modules/unified/index.js:426:11)\n at Function.use (~/node_modules/unified/index.js:165:5)\n β¦\n```\n\n### `processor.parse(file)`\n\nParse text to a syntax tree.\n\n> π **Note**: `parse` freezes the processor if not already\n> *[frozen][api-freeze]*.\n\n> π **Note**: `parse` performs the [parse phase][overview], not the run phase\n> or other phases.\n\n###### Parameters\n\n* `file` ([`Compatible`][vfile-compatible]) β file to parse; typically\n `string` or [`VFile`][vfile]; any value accepted as `x` in `new VFile(x)`\n\n###### Returns\n\nSyntax tree representing `file` ([`Node`][node]).\n\n###### Example\n\nThis example shows how `parse` can be used to create a tree from a file.\n\n```js\nimport remarkParse from 'remark-parse'\nimport {unified} from 'unified'\n\nconst tree = unified().use(remarkParse).parse('# Hello world!')\n\nconsole.log(tree)\n```\n\nYields:\n\n```js\n{\n type: 'root',\n children: [\n {type: 'heading', depth: 1, children: [Array], position: [Object]}\n ],\n position: {\n start: {line: 1, column: 1, offset: 0},\n end: {line: 1, column: 15, offset: 14}\n }\n}\n```\n\n### `processor.parser`\n\nParser to use ([`Parser`][api-parser], optional).\n\n### `processor.process(file[, done])`\n\nProcess the given file as configured on the processor.\n\n> π **Note**: `process` freezes the processor if not already\n> *[frozen][api-freeze]*.\n\n> π **Note**: `process` performs the [parse, run, and stringify\n> phases][overview].\n\n###### Signatures\n\n* `processor.process(file, done)`\n* `Promise