final class Measuring<T> {

    enum Result {
        case success
        case failure(expected: Complexity, result: String)
    }

    enum Complexity {
        case constant
        case logarithmic
        case linear
        case quasiLinear
        case quadratic
        case cubic
        case exponential
        case factorial
    }

    var resource: T

    init(_ resource: T, setUp: ((inout T) -> Void)? = nil) {
        self.resource = resource
        setUp?(&self.resource)
    }

    @discardableResult func assertComplexity <U> (
        _ complexity: Complexity,
        setUp: ((inout T) -> Void)? = nil,
        for operation: (T) -> U
    ) -> Measuring
    {
        // assert ...
        return self
    }