Instance Method
startSpan(_:context:ofKind:at:function:file:line:)
func startSpan<Instant>(_ operationName: String, context: @autoclosure () -> ServiceContext, ofKind kind: SpanKind, at instant: @autoclosure () -> Instant, function: String, file fileID: String, line: UInt) -> InMemorySpan where Instant : TracerInstant