Arash

in chapter 5, the `co2` dataset did not exist in the `efficient` package. I've also checked the repo of the package but I found nothing.

- in section 2.3.1, ["althogh"](https://github.com/csgillespie/efficientR/blob/6a5b604ebb56610d9c69b871fd0fee261e653d35/02-set-up.Rmd#L132) instead of "although". - in section 6.4.1, ["(\\)"](https://github.com/csgillespie/efficientR/blob/6a5b604ebb56610d9c69b871fd0fee261e653d35/06-data-carpentry.Rmd#L299) instead of "(`)". - in section 5.3, you used [`df_co2_dt`](https://github.com/csgillespie/efficientR/blob/6a5b604ebb56610d9c69b871fd0fee261e653d35/05-input-output.Rmd#L109) variable name for `readr::read_csv()`. - in section...

in chapter 3, instead of `seq_along(x)` you used [`seq_len(n)`](https://github.com/csgillespie/efficientR/blob/6a5b604ebb56610d9c69b871fd0fee261e653d35/03-programming.Rmd#L59) which is wrong.

- in [exercise 19.7.5](https://adv-r.hadley.nz/quasiquotation.html#exercises-60), in first question , it makes an error be just by replacing `reduce(summands, call2, "+")` . thus it should be `reduce(summands, call2, .fn = "+")`. -...

the trees in first question of [exercise 18.2.4](https://adv-r.hadley.nz/expressions.html#exercises-52) looks something like this: 

[in first graph](https://d33wubrfki0l68.cloudfront.net/2510d3fbdee75304b97768cae6522820cfbdc80d/08c9c/diagrams/s4/emoji.png) in chapter 15 "😗" emoji inherits form itself. is there any point about that? or it's just a mistake?

R6 vignettes are removed from package, so it's better to use [performance document link](https://r6.r-lib.org/articles/Performance.html) in [this line](https://github.com/hadley/adv-r/blob/714f95f03191f9f2a25b3195f4aeacbd294fc543/R6.Rmd#L607) instead of `vignette("Performance","R6")`.

in [this line](https://github.com/hadley/adv-r/blob/714f95f03191f9f2a25b3195f4aeacbd294fc543/Environments.Rmd#L148) `Rf_GlobalEnv` have an additional "f".

in chapter 8, section 8.5.2. [meangingful](https://github.com/hadley/adv-r/blob/714f95f03191f9f2a25b3195f4aeacbd294fc543/Conditions.Rmd#L775)

I checked the figures and I think fig. 11.6 and fig. 11.7 in the code are fig. 11.5 and fig. 11.6 in the textbook.