Standard updoc prelude for awt and swing
The following line
declares to updoc that further updoc passages on this page are in E 0.9 syntax.
The inner expression on following line
asks the current vat to become a vat executing within the AWT event loop. It returns a promise which will resolve once the request is either completed or refused.
The "interp.waitAtTop/1" pauses the command-line interpreter until its argument promise resolves. Assuming it's successful, further updoc passages on this page can now use AWT and Swing.