Kaba class BeatSource ed

class BeatSource extends Module
    var name: string
    var out_changed: source
    var out_play_end_of_stream: source
    var out_read_end_of_stream: source
    var out_state_changed: source
    var out_tick: source
    var output: OutPort
    var port_out: OutPort&[]
    var session: Session&

    # constructors
    func mut __init__()

    # functions
    func virtual beat_fraction() -> f32
    func virtual beats_per_bar() -> i32
    func virtual cur_bar() -> i32
    func virtual cur_beat() -> i32
    func mut virtual read(out beats: Beat[], samples: i32) -> i32
    func mut virtual read_beats(port: i32, out beats: Beat[], samples: i32) -> i32