Use parentheses

[krlmlr]

when referring to a function in documentation.

Only looked at `` at the start of a line and at surroundings. I can hunt for other instances if you think it's useful.

sed -r -i "" 's/(^#'"'"' `[a-z_]+[a-z_0-9]*)`/\1()`/' R/*

[clauswilke]

Looks good to me. If you can find other instances that'd be great, otherwise we can just merge this one.

[krlmlr]

Thanks. If you merge this I can do a second PR.