16.16 Do repeat yourself

Self-contained documentation vs. DRY (don’t repeat yourself)
Limit user frustration resulting from navigating multiple help files
Two ways to handle:
1. @inheritParams: reuse parameter documentation
  - From source @inheritParams function
  - From another package @inheritParams package::function

#' @param a This is the first argument.
foo <- function(a) a + 10

#' @param b This is the second argument.
#' @inheritParams foo
bar <- function(a, b) {
  foo(a) * 10
}

# Equivalent to

#' @param a This is the first argument.
#' @param b This is the second argument.
bar <- function(a, b) {
  foo(a) * 10
}

@describeIn or @rdname: document multiple functions in one place
- Use with caution. Can lead to confusing documentation.
- See the foobar example
- See the arithmetic example