myFunction <- function () {
  print ('myFunction!')
}
demoFunction <- function (a, b, c) {
     cat ('a=', a, 'b=', b, 'c=', c)
}
sumFunction <- function (a, b, c) {
   sum = a + b + c
   return (sum)
}
myFunction()

demoFunction(1,2,3)

sumFunction(1,2,6)