Please forgive my #rstats ignorance, but where can I go to learn about what double-bang `!!` and triple-bang `!!!` notation mean in R? Is it an {rlang} thing? A tidyeval thing? A something-else thing? And where it is explained?
Example: a bit ways down this section, there's code that defines a list called `cards`, then later references that list as `!!!cards`.
https://rstudio.github.io/bslib/articles/dashboards/index.html#hello-dashboards
I'm not sure exactly what's going on there.
@capbri @kellybodwin you've already gotten some great serious suggestions in the replies, so instead now I'm thinking ... somebody should make an animation illustrating what's going on when you use `!!` and `!!!` to inject arguments 
*cough, cough* @andrew
help("!!")
@capbri @kellybodwin @jennybryan https://rlang.r-lib.org/reference/topic-inject.html
The injection operators are extensions of R implemented by rlang to modify a piece of code before R processes it. There are two main families: The dynamic dots operators, !!! and "{". The metaprogramming operators !!, {{, and "{{". Splicing with !!! can also be done in metaprogramming context.
rlang.r-lib.org