I love the branding "custom functions without code" right before a bunch of code. Reminds me how early word processors (the person, not the software) were convinced to program word processors (the software this time) just by calling the programs "macros". I'm not joining Microsoft's beta program right now, but I'm curious if anyone knows the data type of a =LAMBDA?
(This was Multics Emacs, a predecessor to GNU Emacs.)