The ellipses can be used to pass on arguments to other functions that are

used within the function you're writing. Usually a function that has the

ellipses as an argument has the ellipses as the last argument. The usage of

such a function would look like:

ellipses_func(arg1, arg2 = TRUE, ...)

In the above example arg1 has no default value, so a value must be provided

for arg1. arg2 has a default value, and other arguments can come after arg2

depending on how they're defined in the ellipses_func() documentation.

Interestingly the usage for the paste function is as follows:

paste (..., sep = " ", collapse = NULL)

Notice that the ellipses is the first argument, and all other arguments after

the ellipses have default values. This is a strict rule in R programming: all

arguments after an ellipses must have default values. Take a look at the

simon_says function below:

simon_says <- function(...){

paste("Simon says:", ...)

}

The simon_says function works just like the paste function, except the

begining of every string is prepended by the string "Simon says:"

Telegrams used to be peppered with the words START and STOP in order to

demarcate the beginning and end of sentences. Write a function below called

telegram that formats sentences for telegrams.

For example the expression telegram("Good", "morning") should evaluate to:

"START Good morning STOP"

telegram <- function(...){ paste("START",...,"STOP") }