Function hover 

pub fn hover(source: &str, offset: usize) -> Option<HoverInfo>

Returns hover documentation for the symbol at byte offset in source.

Looks up the innermost AST node whose span contains offset and returns relevant documentation:

• Scalar types -> SQL mapping and description.
• Identifiers matching a model name -> model summary.
• Identifiers matching an enum name -> enum variant list.
• Field declarations -> field type and modifiers.