Remove internal functions from exports

[judith-bourque]

To do

• Add @noRd
• Remove @keywords internal
• Remove @export

Example

To respect the tidyverse style guide and prevent warning messages, document internal functions like this:

#' Drop last
#'
#' Drops the last element from a vector.
#'
#' @param x A vector object to be trimmed.
#' 
#' @noRd # Prevents an Rd from appearing

Notes

The following example will produce a warning message as @export makes the function available to users, but they don't have access to the .Rd file for documentation.

#' Drop last
#'
#' Drops the last element from a vector.
#'
#' @param x A vector object to be trimmed.
#' 
#' @noRd
#' @export

Adding @keywords internal can be appealing, but it's redundant as there's no .Rd file and the function isn't available to users as @export isn't used.