mdast Heading Style Utility

mdast-util-heading-style is a focused utility designed to determine the style of a heading within an `mdast` (Markdown Abstract Syntax Tree) node. It identifies if a heading was authored using ATX (hashes, e.g., `## Heading`), ATX-closed (e.g., `## Heading ##`), or Setext (underline, e.g., `Heading\n===`) Markdown syntax. The package is currently at version 3.0.0 and operates within the broader `unified` ecosystem, often leveraged by linting tools like `remark-lint`. Its release cadence is tied to Node.js LTS versions, with major releases typically dropping support for unmaintained Node.js versions. A key differentiator is its precise, narrow scope: providing just the heading style information, rather than modifying or transforming the AST, making it a reliable building block for more complex Markdown processing pipelines. It is an ES module (ESM) only.