The tricky bit is that a lot of scripting/programming languages reserve the backslash for special stuff. For example, “\n” means a line break. When you pasted the right arm (which is seen on the left ; ) ), lemmy’s editor expected a special thingy, so it was kind and removed the backslash for you, so that you don’t have to. The secret is to post it with a double backslash, like this: “\” (for example, I actually had to use FOUR backslashes in a row, since it’s two double backslashes, because each means one backslash).
EDIT: Lol, I have bamboozled myself, too. I had to edit this a few times.