Function highlight_code 

pub fn highlight_code(
    code: &str,
    lang: &str,
    theme: &Theme,
) -> Option<Vec<Vec<(String, Style)>>>

Highlight source code using tree-sitter.

Returns Some(lines) where each line is a Vec<(text, style)> of styled segments, or None if:

• The language is not recognised
• The corresponding syntax-* feature is not enabled
• Parsing fails

Callers should fall back to the built-in keyword highlighter when None is returned.

Example

let lines = slt::syntax::highlight_code("let x = 1;", "rust", &theme);