diff --git a/.gitignore b/.gitignore
index ecbdc2385f..80f7631497 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,4 @@
+/*.ys
 /Cache/
 /Meta/
 /rosettacode.log
diff --git a/Lang/YAMLScript/Luhn-test-of-credit-card-numbers b/Lang/YAMLScript/Luhn-test-of-credit-card-numbers
new file mode 120000
index 0000000000..f96e4c4d21
--- /dev/null
+++ b/Lang/YAMLScript/Luhn-test-of-credit-card-numbers
@@ -0,0 +1 @@
+../../Task/Luhn-test-of-credit-card-numbers/YAMLScript
\ No newline at end of file
diff --git a/Lang/YAMLScript/Validate-International-Securities-Identification-Number b/Lang/YAMLScript/Validate-International-Securities-Identification-Number
new file mode 120000
index 0000000000..40c80b8d7d
--- /dev/null
+++ b/Lang/YAMLScript/Validate-International-Securities-Identification-Number
@@ -0,0 +1 @@
+../../Task/Validate-International-Securities-Identification-Number/YAMLScript
\ No newline at end of file
diff --git a/Task/Best-shuffle/YAMLScript/best-shuffle.ys b/Task/Best-shuffle/YAMLScript/best-shuffle.ys
index 2874ddd1dd..40b2a8e761 100644
--- a/Task/Best-shuffle/YAMLScript/best-shuffle.ys
+++ b/Task/Best-shuffle/YAMLScript/best-shuffle.ys
@@ -1,8 +1,9 @@
 !YS-v0
 
-defn main(input):
-  say: read-string(input)
-         .map(best-shuffle):vec
+defn main(*inputs):
+  each input inputs: !:say
+    apply format '%s, %s, (%d)':
+      best-shuffle(input)
 
 defn best-shuffle(s):
   ref =: s:group-indices:cycles
diff --git a/Task/Even-or-odd/YAMLScript/even-or-odd.ys b/Task/Even-or-odd/YAMLScript/even-or-odd.ys
index c0a1aa7de0..36ee519cd2 100644
--- a/Task/Even-or-odd/YAMLScript/even-or-odd.ys
+++ b/Task/Even-or-odd/YAMLScript/even-or-odd.ys
@@ -1,6 +1,7 @@
 !YS-v0
 
-defn main(x):
-  if x:even?:
-    say: "$x is even"
-    say: "$x is odd"
+defn main(*xs):
+  each x xs:
+    if x:even?:
+      say: "$x is even"
+      say: "$x is odd"
diff --git a/Task/Factorial/YAMLScript/factorial.ys b/Task/Factorial/YAMLScript/factorial.ys
index 06c6ba6aef..29d50ba6fa 100644
--- a/Task/Factorial/YAMLScript/factorial.ys
+++ b/Task/Factorial/YAMLScript/factorial.ys
@@ -1,7 +1,10 @@
 !YS-v0
 
-defn main(n=10):
-  say: "$n! -> $factorial(n)"
+defn main(*ns):
+  each n ns:
+    say: "$n! -> $factorial(n)"
 
 defn factorial(x):
-  2 .. x: .mul(*)
+  if x <= 2:
+    (x ||| 1)
+    (2 .. x).mul(*)
diff --git a/Task/Function-definition/Tcl/function-definition-3.tcl b/Task/Function-definition/Tcl/function-definition-3.tcl
new file mode 100644
index 0000000000..e2a1260e67
--- /dev/null
+++ b/Task/Function-definition/Tcl/function-definition-3.tcl
@@ -0,0 +1,13 @@
+proc multiply { a b args } {
+
+    set product 1
+
+    foreach m [list $a $b {*}$args] {
+
+	    set product [expr {$product * $m}]
+    }
+
+    return $product
+}
+
+puts stdout [multiply  3 4 7 9 -2 -5 ]
diff --git a/Task/Greatest-common-divisor/Elena/greatest-common-divisor.elena b/Task/Greatest-common-divisor/Elena/greatest-common-divisor.elena
index 8d3b778db8..5dd09f89da 100644
--- a/Task/Greatest-common-divisor/Elena/greatest-common-divisor.elena
+++ b/Task/Greatest-common-divisor/Elena/greatest-common-divisor.elena
@@ -17,7 +17,7 @@ gcd(a,b)
 
 printGCD(a,b)
 {
-    console.printLineFormatted("GCD of {0} and {1} is {2}", a, b, gcd(a,b))
+    Console.printLineFormatted("GCD of {0} and {1} is {2}", a, b, gcd(a,b))
 }
 
 public program()
diff --git a/Task/Luhn-test-of-credit-card-numbers/YAMLScript/luhn-test-of-credit-card-numbers.ys b/Task/Luhn-test-of-credit-card-numbers/YAMLScript/luhn-test-of-credit-card-numbers.ys
new file mode 100644
index 0000000000..6a2092d4d6
--- /dev/null
+++ b/Task/Luhn-test-of-credit-card-numbers/YAMLScript/luhn-test-of-credit-card-numbers.ys
@@ -0,0 +1,10 @@
+!YS-v0
+
+defn main(*nums):
+  each cc nums:
+    say: "$cc - $if(cc:luhn? 'valid' 'invalid')"
+
+defn luhn?(cc):
+  map(mul cc:digits:reverse [1 2]:cycle)
+    .map(\(I(_ / 10) + (_ % 10))):sum
+    .mod(10):zero?
diff --git a/Task/Validate-International-Securities-Identification-Number/YAMLScript/validate-international-securities-identification-number.ys b/Task/Validate-International-Securities-Identification-Number/YAMLScript/validate-international-securities-identification-number.ys
new file mode 100644
index 0000000000..3633f68190
--- /dev/null
+++ b/Task/Validate-International-Securities-Identification-Number/YAMLScript/validate-international-securities-identification-number.ys
@@ -0,0 +1,18 @@
+!YS-v0
+
+defn main(*nums):
+  each isin nums:
+    say: "$isin - $if(isin:isin? 'valid' 'invalid')"
+
+defn isin?(isin):
+  isin.re-matches(/[A-Z]{2}[A-Z0-9]{9}[0-9]/) &&
+  isin.map(b36-10).apply(str):luhn?
+
+defn b36-10(c):
+  c =: c:I - 48
+  if c > 9: (c - 7) c
+
+defn luhn?(cc):
+  map(mul cc:digits:reverse [1 2]:cycle)
+    .map(\(I(_ / 10) + (_ % 10))):sum
+    .mod(10):zero?