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: plot.rs
    path of file: ./repos/glicol/rs/synth/examples
    
    the code of the file until where you have to start completion: use gnuplot::*;
use glicol_synth::{ 
    AudioContextBuilder,
    oscillator::{SinOsc},
    operator::Mul
};

fn main () {

    let mut context = AudioContextBuilder::<128>
    
fn main () {

    let mut context = AudioContextBuilder::<128>::new()
    .sr(44100).channels(1).build();
    let node_a = context.add_mono_node( SinOsc::new().freq(2.) );
    let node_b = context.add_mono_node( Mul::new(0.5) );
    // context.connect(node_a, context.destination);
    context.chain(vec![node_a, node_b, context.destination]);

    // plot part
    let mut x = Vec::<i32>::new();
    let mut y = Vec::<f32>::new();
    let mut n = 0;

    for _ in 0..( 88000 / 128) {
        let buf = context.next_block();
        for i in 0..128 {
            x.push(n);
            n += 1;
            y.push(buf[0][i]); // use the buf here
        };
    }

    let mut fg = Figure::new();
    fg.axes2d()
        .set_title("Glicol output", &[])
        .set_legend(Graph(0.5), Graph(0.9), &[], &[])
        .lines(
            &x,
            &y,
            &[Caption("left")],
        );
    fg.show().unwrap();
}