     /// to you, use the value() method.
     ///
     /// - returns: An optional *Value*.
+    @warn_unused_result
     public func failableValue<Value: DatabaseValueConvertible>() -> Value? {
         return Value.fromDatabaseValue(self)
     }

    /// failableValue() method.
    ///
    /// - returns: An optional *Value*.
    public func value<Value: DatabaseValueConvertible>() -> Value? {
        if let value = Value.fromDatabaseValue(self) {
            return value
        }
        precondition(isNull, "could not convert \(self) to \(Value.self).")
        return nil
    }
    

    /// can not be converted to `Value`.
    ///
    /// - returns: A *Value*.
    @warn_unused_result
    public func value<Value: DatabaseValueConvertible>() -> Value {
        guard let value = Value.fromDatabaseValue(self) as Value? else {
            fatalError("could not convert \(self) to \(Value.self).")
