@DavidCarlisle -- I like it. List of typos in email.

@sunil ask a question on the main site and build an MWE, please.

@DavidCarlisle you were busy ;-). The red color in the examples is nice. I think I would split it over two pages like the other lessons to avoid too much info in one go. One could do on the first page only a "training of the eye" without explanations. That means something like "Undefined command give this error: .... Try it out and look if you can find the error message. Then correct the document." Perhaps there should be also a missing begin document example.

@DonHosek Paloma is a Brazilian name too. :)

@UlrikeFischer I was just about to ask @JosephWright if he saw last night's discussion with you and @barbarabeeton about an error page davidcarlisle.github.io/ll/en/extra-02.html now has Barbara's shocking comments about my typos addressed. Not sure whether it is best as an extra-xx or to make it lesson-15/more-15 and move the current lesson-15 to 16 ? You can now use the kramdown {: .noedit :} to suppress edit/copy buttons being added to <pre> blocks

@DavidCarlisle ooh lesson-15-fixed

@PauloCereda more topical lesson-15-full-of-errors

@DavidCarlisle ooh

@DavidCarlisle also quack

@PauloCereda brunch

@DavidCarlisle oh no

@DavidCarlisle Extras-15 sounds good

@JosephWright extras-02 or lesson-15 ?

@JosephWright 'ello mr. duck

@DavidCarlisle extras-15

% arara: lualatex
% arara: lualatex
% arara: ghostscript: {  resolution: 250  , device: png16m}

% arara: cleanx: { extensions: [ aux , toc , log , bbl , bcf , blg , out , run.xml, gz, listing ] }

\documentclass[a4paper]{article}
\usepackage[margin=20mm, paperheight=33cm]{geometry}
\usepackage{tikz}

% stepcolors
\foreach \N/\n in {0/black, 1/brown, 2/red!70,
3/orange, 4/yellow!80!orange, 5/green!70!black,
6/blue!50, 7/violet!60, 8/gray}{
\xglobal\colorlet{stepcolor\N}{\n}
}
\makeatletter
\def\IsColorDefined#1{\@ifundefined{\string\color@#1}{black}{#1}}

@cis take a look at the .search also handler of pgfkeys.

@Skillmonlikestopanswers.xyz Aaahhhaaa.... So I need:

\pgfkeys{/cis/.is family,     /cis/.cd,
/cis/.search also={/tikz,/pgf},
}

Finally getting around to installing TL2020. First had to update MacOS to Mojave.

Yay! Then Big Sur soon! :)

@PauloCereda El país grande del sur?

@StefanKottwitz no hablo su idioma, señor. :)

Und ich spreche kein Spanisch. :)

@PauloCereda su? tu!

Nur ein bussen Portugiesisch. :)

@StefanKottwitz ooh truco

@PhelypeOleinik ˆˆ

@PauloCereda Ein bisschen ;)

@TeXnician oopsie

Ich essen kartoffel

@PauloCereda obrigado pato :-)

I better shut up. :)

@StefanKottwitz ooh <3

@PauloCereda Ich esse (without n) Kartoffeln (here there's a n) :D

@TeXnician oh my

@TeXnician @StefanKottwitz sorry for butchering your beautiful language

@PauloCereda Thanks in the name of tender delicate sensible GeRRmansss!

@StefanKottwitz oh

@PauloCereda O que seriam as batatas sem um pato?

ooh how does one say French fries in German? Fried Kartoffeln? :)

we may say Pommes or Fritten

ooh

Heute esse Ich Fritten, das ist sehr gut!

Le patatine frite

@CarLaTeX ˆˆ

@PauloCereda Isso é perfeito e delicioso!

@StefanKottwitz it is! :)

@PauloCereda Buone!!!

@PauloCereda La Nutella è buona ma non sulla pizza

@CarLaTeX oh no

@CarLaTeX Não esqueça o abacaxi!

@StefanKottwitz LOL

@StefanKottwitz Oh no!

@CarLaTeX oh no

@PauloCereda Not likely. I'm already avoiding Catalina. Various old apps that won't work on it.