The standard library io_startup_and_shutdown__premicrothread package implements functionality for registering functions to be run at system startup or shutdown, corresponding to the microthread-level package io_startup_and_shutdown.
The io_startup_and_shutdown__premicrothread package implements the Io_Startup_And_Shutdown__Premicrothread api.
The io_startup_and_shutdown__premicrothread package source code is in src/lib/std/src/io/io-startup-and-shutdown–premicrothread.pkg. The above information is manually maintained and may contain errors.
Io_Startup_And_Shutdown__Premicrothread