Add tasks for all the new languages

Task/Combinations/Sidef/combinations-3.sidef

@@ -0,0 +1,31 @@
+func forcomb(callback, n, k) {
+
+    if (k == 0) {
+        callback([])
+        return()
+    }
+
+    if (k<0 || k>n || n==0) {
+        return()
+    }
+
+    var c = @^k
+
+    loop {
+        callback([c...])
+        c[k-1]++ < n-1 && next
+        var i = k-2
+        while (i>=0 && c[i]>=(n-(k-i))) {
+            --i
+        }
+        i < 0 && break
+        c[i]++
+        while (++i < k) {
+            c[i] = c[i-1]+1
+        }
+    }
+
+    return()
+}
+
+forcomb({|c| say c }, 5, 3)