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: audio_emitter.rs
    path of file: ./repos/amethyst/amethyst_audio/src/components
    
    the code of the file until where you have to start completion: use std::{
    io::Cursor,
    sync::{atomic::AtomicBool, Arc},
};

use rodio::{Decoder, SpatialSink};
use smallvec::SmallVec;

use crate::{components, source::Source, DecoderError};

/// An audio source, add this component to anything that emits sound.
/// TODO: This should get a proper Debug impl parsing the sinks and sound queue
#[allow(missing_debug_implementations)]
#[derive(Default)]

    
    fn test_picker() {
        // Create the input variables
        let mut emitter_main = AudioEmitter::default();
        let box_picker: Box<dyn FnMut(&mut AudioEmitter) -> bool + Send + Sync> =
            Box::new(use_audio_emitter);

        // Test set_picker and assert that it is not empty
        emitter_main.set_picker(box_picker);
        assert!(emitter_main.picker.is_some());

        // Test clear_picker and assert it is empty
        emitter_main.clear_picker();
        assert!(emitter_main.picker.is_none());
    }