C-f to the beginning of each character group and add whitespace.
You can also set mark at first 'b' in the first line, go to first 'b' in the last line and use C-x r t to insert a string across all the lines.
You can of course use regex-replace, too: \(a+\|b+\|c+\|d+\) -> \1 <- space here
And so on and on. It's good to see well written "introductory courses", like this one, but what about "Emacs for black belts"? "Advanced Emacsology"? There is one book about writing Emacs extensions (http://shop.oreilly.com/product/9781565922617.do), but that's all there is. Does anyone know about another source of knowledge about the most advanced Emacs techniques?
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