import Benchmark
Benchmark.measure() {
    print(self) // don't have to set weak.
    for _ in 0...10000000 { }
}
// Benchmark: 0.1690970063 sec.
// Benchamrk can be set name.
Benchmark.measure("Measure1") {
    for _ in 0...10000000 { }
}
// Measure1: 0.1690970063 sec.

import Benchmark
func heavyMethod() {
    let outer = Benchmark(key: "outer")
    let inner = Benchmark(key: "inner")
    // some light processes
    for _ in 0...10 { }
    inner.finish()  // inner: 0.0002210140 sec.
    // some heavy processes
    for _ in 0...10000000 { }
    outer.finish()  // outer: 0.1663100123 sec.
}

import Benchmark
class Foo {
    func execute() {
        Benchmark.start()
    }
}
class Bar {
    func execute() {
        Benchmark.finish()
    }
}
Foo().execute()
Bar().execute()  // Benchmark: 0.0001509786 sec.

import Benchmark
// same as Benchmark.measure {}
⏲{
    for _ in 0...10000000 { }
}
// Benchmark: 0.1653281017 sec.