Function hover_info 

pub fn hover_info(
    ast_data: &Value,
    file_uri: &Url,
    position: Position,
    source_bytes: &[u8],
    gas_index: &GasIndex,
    doc_index: &DocIndex,
    hint_index: &HintIndex,
) -> Option<Hover>

Produce hover information for the symbol at the given position.