In the example function below how can one tell whether `a`, `b` or `c` are input or output values, other than from the context?

Also, if `example()` is called is a value assigned to `c` outside the scope of `example()`?

```
function example(a, b, c)
   real*8 a, b, c
   c = a + b
   example = c
end function example

```