https://rtorrent-docs.readthedocs.io/en/latest/cmd-ref.html#string-functions

• ✔️ Update / finish documentation
• ✔️ UTF8 support for all this!
• ✔️ string.len → value
• ✔️ string.substr → string
• ✔️ string.strip → string (optional char sequence to strip, lstrip / rstrip?)
• ✔️ string.replace → string
• ✔️ string.map → string
• ✔️ string.split → list
• ✔️ string.join → string – like cat, but with a delimiter
• ✔️ string.contains[_i] → value
• ✔️ string.equals → value
• ✔️ string.endswith → value
• ✔️ string.startswith → value
• ❌ string.chop – see string.substr
• ✔️ string.[lr]pad → string