The `AHI` variable is an AHK class that makes it easy to interact with the AutoHotInterception DLL (Which itself then interacts with the Interception dll). For example, it wraps `GetDeviceList()` to make it return a normal AHK array. Most of the time you will not need it.
For advanced users, if you wish to directly communicate with the AHI DLL (eg for best possible performance), you can call `AHI.Instance` instead of `AHI` for most functions (eg when sending of synthesized input using `SendMouseMove`).