The format_aid function formats (numeric) AID IDs into character strings
of a predefined length (parameter length) adding leading "0"s to the
provided ID (x).
format_aid(x, length = 10)numeric with the IDs to format.
integer(1) defining the length (in characters) of the AID
format.
character with the formated AID.
format_aid(c(1, 2, 3))
#> [1] "0000000001" "0000000002" "0000000003"
## IDs provided as `character` are not formatted.
format_aid("hello")
#> [1] "hello"