Function builtin_slot 

fn builtin_slot(
    args: &[RValue],
    _named: &[(String, RValue)],
) -> Result<RValue, RError>

Extract a slot from an S4 object.

Extracts a named element from the underlying list, equivalent to the @ operator.

@param object an S4 object (list with class attribute) @param name character string naming the slot @return the slot value, or an error if the slot doesn’t exist