Function async_enter 

pub fn async_enter<C: CategoryString, S: AsTraceStrRef>(
    id: Id,
    category: C,
    name: S,
    args: &[Arg<'_>],
) -> AsyncScope<C, S>

Writes an async event which ends when the current scope exits, or the end method is is manually called.

Async events describe concurrently-scheduled work items that may migrate between threads. They may be nested by sharing id, and are otherwise differentiated by their id.

0 to 15 arguments can be associated with the event, each of which is used to annotate the duration with additional information.