You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: rectangle.rs
    path of file: ./repos/conrod/conrod_core/src/widget/primitive/shape
    
    the code of the file until where you have to start completion: //! A simple, non-interactive rectangle shape widget.
//!
//! Due to the frequency of its use in GUIs, the `Rectangle` gets its own widget to allow backends
//! to specialise their rendering implementations
    
    fn update(self, args: widget::UpdateArgs<Self>) -> Self::Event {
        let widget::UpdateArgs { state, style, .. } = args;

        let kind = match *style {
            Style::Fill(_) => Kind::Fill,
            Style::Outline(_) => Kind::Outline,
        };

        if state.kind != kind {
            state.update(|state| state.kind = kind);
        }
    }