Kaba class PitchRenderer ed

class PitchRenderer
    var delta_phi: f32
    var pitch: i32
    var synth: Synthesizer&

    # constructors
    func mut __init__(synth: Synthesizer, pitch: i32)

    # functions
    func mut virtual on_config()
    func mut virtual on_end()
    func mut virtual on_start(volume: f32)
    func mut virtual render(out buf: AudioBuffer) -> bool