Spyglass expands on the ideas outlined in this paper by the Brave Search Team to allow users to define what should / should not be crawled and indexed for topics they're interested in.
Open the "My Library" window bygoing into the system tray menu and clicking on
My Library option. This will open a window like below:
Here you can view the progress of any crawls or lenses being installed.
will bring up the source code for the lens configuration.