Add all the A tasks

Task/Anonymous-recursion/C/anonymous-recursion.c

@@ -0,0 +1,29 @@
+#include <stdio.h>
+
+long fib(long x)
+{
+        long fib_i(long n) { return n < 2 ? n : fib_i(n - 2) + fib_i(n - 1); };
+        if (x < 0) {
+                printf("Bad argument: fib(%ld)\n", x);
+                return -1;
+        }
+        return fib_i(x);
+}
+
+long fib_i(long n) /* just to show the fib_i() inside fib() has no bearing outside it */
+{
+        printf("This is not the fib you are looking for\n");
+        return -1;
+}
+
+int main()
+{
+        long x;
+        for (x = -1; x < 4; x ++)
+                printf("fib %ld = %ld\n", x, fib(x));
+
+        printf("calling fib_i from outside fib:\n");
+        fib_i(3);
+
+        return 0;
+}