Kaba struct BarCollection ed

struct BarCollection extends shared![Bar][]
    var num: i32

    # constructors
    func mut __init__()

    # functions
    func selfref get_bars(r: Range) -> Bar&[]
    func selfref get_beats(r: Range, include_hidden: bool, sub_beat_partition: i32?) -> Beat[]
    func get_next_beat(pos: i32) -> i32
    func get_prev_beat(pos: i32) -> i32

    # operators
    func selfref __subarray__(start: i32, end: i32) -> BarCollection # BarCollection[int:int] -> BarCollection
    func mut __assign__(other: BarCollection) # BarCollection = BarCollection