Text Handling: Parse and Transform Rich-Text Markup into Plain Text

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## Problem You are given a string containing a simple markup language with tags `[b]`, `[i]`, `[u]`, `[link=url]`, and `[/tag]`. Implement a parser that strips all markup and returns clean plain text. Additionally, implement a renderer that converts markup to HTML equivalents. ```python class TextHandler: def __init__(self, markup: str): ... def to_plain(self) -> str: ... def to_html(self) -> str: ... def extract_links(self) -> list[str]: ... ``` ## Example ``` Input: "Hello [b]world[/b]! Visit [link=https://example.com]our site[/link]." to_plain() -> "Hello world! Visit our site." to_html() -> 'Hello world! Visit our site.' extract_links() -> ["https://example.com"] ``` ## Follow-ups 1. How do you handle malformed or unclosed tags gracefully? 2. What if tags can be nested (`[b][i]text[/i][/b]`) — how does your parser handle overlapping? 3. How would you support custom user-defined tags? 4. What are the XSS risks if this output is rendered in a browser and how do you mitigate them?

Text Handling: Parse and Transform Rich-Text Markup into Plain Text

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