Kaba class Runtime ed

class Runtime
    var assumptions: shared![Term][]
    var functions: owned![Function][]
    var history: shared![Term][]

    # constructors
    func mut __init__()

    # functions
    func mut add_function(t: shared![Term])
    func mut eval(s: string) -> shared![Term]
    func mut eval_term(_t: shared![Term]) -> shared![Term]

    # nested classes
    class Function