Recall is used as a placeholder for the name of the function
in which it is called. It allows the definition of recursive
functions which still work after being renamed, see example below.
Recall(...)do.call and call. local for another way to write anonymous recursive functions.
## A trivial (but inefficient!) example:
fib <- function(n)
if(n<=2) { if(n>=0) 1 else 0 } else Recall(n-1) + Recall(n-2)
fibonacci <- fib; rm(fib)
## renaming wouldn't work without Recall
fibonacci(10) # 55
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