Kaba struct Tag ed

struct Tag
    var key: string
    var value: string

    # constructors
    func mut __init__()
    func mut __init__(key: string, value: string)

    # functions
    func static parse(s: string) -> Tag

    # operators
    func __str__() -> string             # str(Tag) -> string
    func mut __assign__(other: Tag)      # Tag = Tag